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Julia Lawall (Inria), Tathagata Roy18/09/2024, 10:00
Coccinelle is a tool for program matching and transformation, relying on semantic patches, which describe code changes in terms of fragments of source code. Coccinelle for C has been extensively used on the Linux kernel. For the past couple of years we have been developing Coccinelle for Rust. This talk will highlight the main progress that has been made in the past year, with respect to...
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Piotr Król (3mdeb)18/09/2024, 10:00
The presentation highlights five challenging areas and activities to address those in various communities over the last two years.
- Lack of OS awareness about hardware security capabilities leads to the inability to evaluate and improve system security posture.
Platform security and the challenges of closing System Management Mode (SMM) created a gap in an open-source way. - The...
- Lack of OS awareness about hardware security capabilities leads to the inability to evaluate and improve system security posture.
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Jonathan Cameron (Huawei Technologies R&D (UK))18/09/2024, 10:00
Key takeaway - interrupts are what makes this complex.
The PCIe port driver is an unusual beast:
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- It binds to several Class Codes because they happen to have common features. (PCI Bridges of various types, Root Complex Event Collectors).
- It then gets ready to register a set of service drivers.
- Before registering those service drivers it has to figure out what interrupts are in use... -
Nishanth Menon (Texas Instruments, Inc), Vignesh Raghavendra18/09/2024, 10:20
We would like to propose a new boot-firmware repository similar to the Linux-firmware repository under the aegis of U-Boot hosting.
In addition to TI [1], it looks like many SoCs (see NXP[2] and Rockchip[3] eg.:) platforms seem to require additional closed-source/open-source binaries to have a complete bootable image. Distribution rights and locations of these binaries are challenging, and...
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Ilpo Järvinen (Intel)18/09/2024, 10:20
PCIe Bandwidth Controller (bwctrl) is a PCIe portdrv service that allows controlling the PCIe Link Speed for thermal and power consumption reasons. The Link Speed control is provided through an in-kernel API and for userspace through a thermal cooling device. With the advent of PCIe gen6, also the PCIe Link Width will become controllable in the near future.
On PCIe side, bwctrl requires...
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Benno Lossin18/09/2024, 10:30
Rust is about more than just memory safety: Several language features provide guardrails that help programmers prevent common mistakes. At the same time, they facilitate the creation of APIs that better convey their intent and make it hard to misuse them.
This presentation provides a gentle and beginner-friendly (no Rust knowledge required) introduction to several of these features....
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Saurabh Singh Sengar (Microsoft), Srivatsa Bhat (Microsoft)18/09/2024, 10:40
The Linux kernel has been observed to take several 10s of seconds to boot-up on machines with many CPUs (~1792 CPUs). This talk delves into the details of bottlenecks uncovered in the CPU online path when testing on large NUMA multi-core virtual machines and outlines some of the fixes that helped achieve up to 50% faster boot times on such VMs. These optimizations range from approaches such as...
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Liang Yan18/09/2024, 10:40
We encountered a performance bottleneck while testing NCCL on a GPU cluster with 8x H100 GPUs and 8x 400G NIC nodes. Despite a theoretical capacity of 400 Gb/s, our system consistently reached only ~85 Gb/s. The primary issue was identified as communication constraints between GPUs and NICs under the same PCIe switch.
This session will concisely overview the challenges we experienced, such...
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Daniel Almeida (Collabora)18/09/2024, 11:00
This talk will show how it is possible to write Rust code without a binding layer, with a focus on V4L2 codec drivers and libraries. It will present a strategy wherein only a few critical functions are converted to Rust while accounting for the role of the "cbindgen" tool in keeping ABI compatibility. The source code of a previously submitted proof-of-concept will be used to provide examples.
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Aleksandr Burmashev (Oracle corporation)18/09/2024, 11:00
at first i want to give a brief description of what SBAT is, why it was implemented and what currently supports it ( grub2, shim, systemd-boot various EFI tools, like fwupdate and etc ).
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And also cover that SBAT expects different downstream distros to adopt upstream SBAT values from the code base they consume, so that a proper revocation by SBAT is always ensured.
And explain why SBAT... -
Mr Jason Gunthorpe (NVIDIA Networking)18/09/2024, 11:00
A brief iommufd update and time for any active discussion that needs resolution.
A discussion on Generic Page Table which should reach the mailing list as RFC before the conference. Generic Page Table consolidates the page table code in the iommu layer into something more like the MM with common algorithms and thin arch specific helpers. Common alogrithms will allow implementing new ops to...
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Matthew Garrett (Google)18/09/2024, 11:20
U-boot is commonly used to provide a UEFI environment on embedded platforms, making it easier to run commodity operating systems. But what about the inverse case, where we want to make a commodity platform look more like an embedded one? U-boot has a less well known feature for being used as a UEFI payload, but it has poor support for generic hardware and doesn't interact well with runtime...
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Mr Andreas Hindborg (Samsung)18/09/2024, 12:00
In this talk we present our efforts on implementing a safe Rust API for the
hrtimersubsystem. The API is used for timer based completions in the Rust null block driver.We discuss application of the "intrusive pattern" first applied in the
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Marta Lewandowska (Red Hat)18/09/2024, 12:00
We are working on a new scheme to replace the GRUB boot loader with a fast, secure, Linux-based, user-space solution: nmbl (for no more boot loader).
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GRUB is a powerful, flexible, fully-featured boot loader used on multiple architectures, but its features create complexity that is difficult to maintain, and that both duplicate and lag behind the Linux kernel while also creating numerous... -
Shivaprasad G Bhat (IBM)18/09/2024, 12:00
PPC64 implementation of VFIO is spread across two vastly different machine types (pSeries, PowerNV) trying to share a lot of common code driven by PPC specific SPAPR IOMMU API.
The support of the PCI device assignment on these sub arch's have gone through many cycles of breakages and fixes with ongoing efforts to add support for IOMMUFD, which PPC64 is yet to catch up to. Enhancements[1] to...
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James Gowans (Amazon EC2)18/09/2024, 12:10
Live update is a mechanism to support updating a hypervisor in a way that has limited impact to running virtual machines. This is done by pausing/serialising running VMs, kexec-ing into a new kernel, starting new VMM processes and then deserialising/resuming the VMs so that they continue running from where they were. When the VMs have DMA devices assigned to them, the IOMMU state and page...
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Mr George Wilson (Security Architect), Nayna Jain18/09/2024, 12:20
Given the present discussions around UKI and nmbl, Linux appears to be headed towards a future where it most commonly boots directly rather than via a separate bootloader. The IBM Linux on Power team agrees that this is a laudable direction: work need not be duplicated between the kernel and bootloaders and the entire class of bootloader-specific bugs - including vulnerabilities - would become...
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Boqun Feng18/09/2024, 12:30
Atomics and memory consistency model are important building blocks for kernel development. Based on a few previous...
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Joel Granados18/09/2024, 12:30
The PCI ATS Extended Capability allows peripheral devices to participate in the
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caching of translations when operating under an IOMMU. Further, the ATS Page
Request Interface (PRI) Extension allows devices to handle missing mappings.
Currently, PRI is mainly used in the context of Shared Virtual Addressing,
requiring support for the Process Address Space Identifier (PASID) capability,
but... -
Lennart Poettering18/09/2024, 12:40
systemd has gained various TPM-related components in the recent past, to make measured boot on generic Linux reality.
In this talk I'd like to shed some light on recent developments in this area, and what comes next. Some of the topics touched will (probably) be:
- Additional PCRs via nvindexes
- Measurement logs
- An API for quotes of system state, and remote attestation
*...
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Srivatsa Vaddagiri (Qualcomm)18/09/2024, 12:50
Platform devices are those that are discovered via something like a device-tree.
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Once discovered, the device is typically available for the life of a VM. IOW
platform devices can't be hotplugged in its typical sense. Qualcomm however is
having usecases where platform device ownership need to be managed at runtime
between VMs. A VM that has ownership of a platform device is required... -
18/09/2024, 13:00
Birds of a feather
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Daniel Smith (Apertus Solutions, LLC), Mr Ross Philipson (Oracle)18/09/2024, 13:00
TrenchBoot is an OSS project that is used to establish the integrity of the loaded software. The previous work was focused on Intel and AMD implementations of their dynamic root of trust mechanisms. Arm, in consultation with members of the TrenchBoot community, designed a DRTM implementation for their platform. This presentation focuses on the initial design work to bring Arm support to the...
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Manivannan Sadhasivam18/09/2024, 13:10
As a follow up to the last year's 'PCI Endpoint Open Items Discussion', below are the topics for discussion this year:
- State of the Virtio support in PCI Endpoint Subsystem
- Using QEMU for testing PCI Endpoint Subsystem
- Repurposing Interrupt Controllers for Receiving Doorbells in Endpoint Devices
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Josef Holzmayr (Mender.io & Yocto Project), Philip Balister (OpenEmbedded)18/09/2024, 15:00
The organizers introduce themselves and set expectations
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André Almeida (Igalia)18/09/2024, 15:00
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Tobias Huschle18/09/2024, 15:00
In virtualized environments, information about the underlying physical CPU topology is usually hidden from the guest systems.
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This talk will discuss challenges in scheduling virtual CPUs and how passing topology insights to the guests can be utilized to allow the guests to cooperate and gain performance benefits.
As an example, the s390 architecture will be used to demonstrate how smart... -
Damien Le Moal (Western Digital), Hans Holmberg, Johannes Thumshirn (Western Digital Corporate)18/09/2024, 15:00
In this session we'll kick off the MC by summing up what has been going on in the Linux zoned storage space since the last LPC MC two years ago.
We'll focus on what is not covered by dedicated sessions later in the afternoon:
- Zoned Mobile flash is now supported in UFS and...
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Helen Koike (Collabora), Sebastian Fricke18/09/2024, 15:05
Everybody seemingly needs CI and a lot of subsystems already have their spin of
CI running, but everyone is cooking their soup, while when we look at it
the majority of what the CI systems do is very, very similar.This proposal aims to highlight the different attempts currently floating
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around (DRM CI, MediaCI, KCI-Gitlab, CKI, Intel XE, etc.), depicting the
large overlaps but also the... -
Chris Simmonds18/09/2024, 15:10
AOSP is a Linux operating system for smart phones, tablets, TVs and many other sorts of device, all of which fall under the broad term "embedded". AOSP has it's own build system, but it shares many characteristics with others. Initially it was based on GNU Make (Buildroot-like), then with Android 8 it began the migration to a new tool called Soong, with recipes written in a format called...
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Shrikanth Hegde18/09/2024, 15:22
CPU capacity is a software construct to reflect underlying physical CPU capacity. Load balancer uses the CPU capacity to choose an optimal CPU for performance and energy efficiency. CPU Capacity can be affected by frequency, higher level sched classes, guest preemption etc. Steal time is an indicator of guest preemption by the host hypervisor. Current Linux scheduler, updates the CPU capacity...
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Dmitry Baryshkov (Linaro Ltd.)18/09/2024, 15:30
While MIPI DSI bus and MIPI devices has been supported in Linux kernel for quite a while, during the last few years several important corner cases were identified, which make it hard to fit the MIPI DSI devices into the standard DRM pre-enable / enable / disable / post-disable model. Some of the shortcomings were solved via the pre_enable_prev_first call, other shortcomings remain unsolvd....
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Jia Li18/09/2024, 15:30
- Let's discuss the state of zoned storage in QEMU and any questions
about using zoned storage in QEMU. - Zoned block devices on Linux can now be exposed to VMs via SCSI ZBC
and virtio-blk emulation. - SCSI devices can also be passed through (scsi-generic) and physical
PCI adapters can be assigned to VMs if you don't want QEMU emulation
involved. - There is work in progress to support...
- Let's discuss the state of zoned storage in QEMU and any questions
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Arnout Vandecappelle (Mind Software Consultancy)18/09/2024, 15:40
Both for security and for license compliance, we need to be able to trace which software (source code) goes into the artefacts we produce. Buildroot and Yocto build systems produce a bill of materials, but is this sufficient? Let's discuss some of the shortcomings and how we can deal with them.
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Mr Qais Yousef (Google)18/09/2024, 15:44
One of the bottlenecks to making progress in scheduler is understanding 'what is the problem?'
Reporters who don't understand the scheduler can't provide useful info to help root cause why they see a problem.
Developers, seasoned or new, can trip over many details and corner cases that might make what appears to be a bug to be actually a feature that is just not well understood by the...
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Hans Holmberg18/09/2024, 15:50
XFS is growing support for Zoned storage, and In this session we'll present and discuss the background, current state(including early benchmarks) and what's next for project, focusing on:
- Space management
- Data placement
- Write throttling and latency management
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Luca Ceresoli (Bootlin)18/09/2024, 16:00
Traditional DRM pipelines for embedded devices have no removable components, while PC-style pipelines have long time supported hotplug of the panel only, via standardized connectors such as HDMI or DisplayPort.
Embedded devices being currently developed by the industry have a video pipeline whose last components, including one or more bridges, are located on a hot-pluggable add-on using a...
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Alejandro Hernandez Samaniego18/09/2024, 16:05
As the landscape of operating systems continues to diversify, there is a growing
interest in running multiple operating systems and applications, each with
different capabilities and functionalities, on a single device.However, how may these applications or operating systems vary from one another?
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The C library plays a crucial role in this. Having the flexibility to choose one
C... -
Xi Wang18/09/2024, 16:07
Throttling-like mechanisms such as CFS bandwidth control, extremely biased cgroup CPU shares and CPU masks can create quasi priorities among CFS tasks, and we can get priority inversion without explicit priority. We had such a problem caused by deep CPU throttling with CFS bandwidth control and it was causing application timeouts and down time.
To solve this problem we created a priority...
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Viacheslav Dubeyko18/09/2024, 16:10
SSDFS natively supports ZNS SSD and is ready to employ FDP-based SSD. SSDFS provides multiple space saving techniques (compression, compaction, inflation model of erase block, deduplication, delta-encoding) that also work as techniques of decreasing write amplification. How do these techniques work together? How efficient could these techniques be for the case of ZNS SSD and FDP-based SSD?...
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Chuck Wolber18/09/2024, 17:00
We recognize Open Source Software as one of humanity's greatest tools for aggregating and disseminating reusable functionality. This supports a dualistic view where individual needs are met while the greater good is altruistically served.
As effective as Open Source Software is at serving its dualistic nature, there is still a tension between the needs of build integrators, who value...
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André Almeida (Igalia)18/09/2024, 17:00
GPU resets are a common problem for every vendor, due to the nature of the stack. A bad shader can put the render node in an infinite loop, and we need to reset the GPU, partially or completely. However, each driver (both at userspace and kernelspace) have different ideas of what to do when a reset happens.
The goal of this session is to try to find a better common ground of how to manage...
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Vincent Guittot (Linaro)18/09/2024, 17:00
The Energy Aware Scheduler has been developed with the assumption that tasks wake up regularly and often enough to keep their placement energy efficient and responsive. This assumption tend to be less and less true because of constraints like capping the performance of the system and the needs for still shorter response time. New mechanisms outside the wakeup path needs to be enabled to solve...
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Bruno Banelli, Luka Perkov, Viacheslav Dubeyko18/09/2024, 17:00
Multiple Virtual Machines (VMs) workload is a widely deployed use-case. Let’s imagine a storage pool that can include multiple ZNS SSDs, SMR HDDs or a mixture of different types of storage devices (and, maybe, some computational power in the storage pool). The crucial question here is how to implement and deliver a flexible and efficient scheme of storage pool’s space distribution and...
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Hans Holmberg, Johannes Thumshirn (Western Digital Corporate)18/09/2024, 17:20
This session is reserved for BOFs dedicated to continued discussions on topics presented earlier in the day (and other issues and ideas we should work on as a community). Contact the organizers if you have something you'd like to bring up.
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Pintu Kumar18/09/2024, 17:22
In any system the overall system congestion behavior mainly revolve around CPU work-load, memory-pressure and IO-wait.
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The Pressure Stall Information (PSI), introduced to monitor resource contention by tracking CPU, memory, and I/O pressure, provides real-time insights into system performance bottlenecks.
But the problem is, it just gives the overall average load value in the system during... -
Josef Holzmayr (Mender.io & Yocto Project)18/09/2024, 17:30
A thriving ecosystem is crucial for every kind of programming language or environment, and a large portion of it is the "batteries included" mindset, respectively reducing the friction of adding libraries.
Enter APMs - Application Package Managers.
From the distribution building point of view, this is a major problem. Reinvented processes time and again, reproducibility blockers,...
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Prakash Gupta (Qualcomm)18/09/2024, 17:30
Kernel supports default cma and system dmabuf heaps. In order to support protected usecase, additional heap types needs to be supported.
There are quite a few downstream dmabuf heaps maintained by vendors to support protected usecase. There is need to provide generic framework, which will reduce fragmentation of such dmabuf heap types.
The proposed restricted dmabuf heaps will support...
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Mr Qais Yousef (Google)18/09/2024, 17:44
Power management features like DVFS introduces Time Dilation effect where progress of time slows down the lower the frequency from the task's perspective.
Combined with Heterogeneous systems (HMP) this Time Dilation become more extreme on the smaller cores. Especially on Arm mobile SoCs where the little cores are too small on many SoCs.
This manifests as big delays in task's rampup...
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Alexander Kanavin (Linutronix / Yocto)18/09/2024, 17:55
The Yocto project is a toolkit for creating custom Linux distributions for the embedded use cases. Historically it has not provided tools and standards for setting up and replicating build configurations in a reproducible manner, leaving that to third party projects and custom scripts. In the past few months this has been changing, and many of the pieces are now available out of the box in...
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18/09/2024, 18:00
This is a open slot that can be used if the MC contributors wants more time to work together in some topic
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John Stultz (Google)18/09/2024, 18:05
At OSPM we had a number of discussions around the need for QoS APIs for applications to hint their needs for latency and throughput for SCHED_NORMAL/FAIR tasks, as opposed to the typical global tuning of scheduler knobs.
Folks seemed generally supportive of adding some sort of hinting API. However, while any hinting API will be coy and resistant to making any hard promises to userland...
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Adam Manzanares (Samsung Electronics), Dan Williams (Intel Open Source Technology Center), Davidlohr Bueso (Samsung Semiconductor), Jonathan Cameron (Huawei Technologies R&D (UK))19/09/2024, 10:00
A brief hello from the CXL uconf organizers.
The usual collection of small administrative elements.
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Lai Jiangshan (AntGroup), Wenlong Hou19/09/2024, 10:00
Nowadays, there are various needs to run a VM in the public cloud, such as running a security container to isolate workloads or encapsulating an application into a VM for migration or rapid kernel testing utilizing cost-effective spot VMs. However, nested virtualization on KVM requires hardware support and is usually disabled by the cloud provider for safety reasons. Additionally, the current...
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Ira Weiny, Jonathan Cameron (Huawei Technologies R&D (UK)), Navneet singh (Intel)19/09/2024, 10:10
CXL - Dynamic Capacity Devices (DCD)
CXL introduced Dynamic capacity device support in CXL 3.0 and 3.1. The feature
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promises a lightweight memory hotplug feature which was designed to optimize
memory usage within data centers. The details of use cases for DCDs are still
playing out. Generally the use case is to reduce the cost of unused memory by... -
Rafael Wysocki (Intel Open Source Technology Center)19/09/2024, 10:10
For the last year the thermal control subsystem in the Linux kernel has been undergoing an extensive redesign resulting in some code simplifications, enhancements and fixes for known issues. However, there are still ways to improve it. Among other things, the following changes may be considered:
- Introduction of a thermal core testing facility.
- Finalizing the elimination of trip point...
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Mingwei Zhang (Google)19/09/2024, 10:30
BACKGROUND
KVM has supported vPMU for years as the emulated vPMU. In particular, KVM presents a virtual PMU to guests where accesses to PMU get trapped and converted into perf events. These perf events get scheduled along with other perf events at the host level, sharing the HW resource. In the emulated vPMU design, KVM is a client of the perf subsystem and has no control of...
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Daniel Lezcano (Linaro)19/09/2024, 10:30
The trip points are used by the kernel to start mitigating a specific thermal zone when a temperature crosses this limit. This action is taken to protect the silicon. The userspace thermal management has a more complex logic where it takes into account multiple sources of information like the temperatures, the usage and the current application profile to sustain the performance. It readjusts...
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Robert Richter (AMD Inc.), Mr Srinivasulu (Srini) Thanneeru, Terry Bowman (AMD)19/09/2024, 10:40
Compute Express Link (CXL) is a low-latency, high-bandwidth, heterogeneous, and cache-coherent interconnect between a CPU or a device and other accelerator or memory devices. With CXL Type 3 Devices the memory is located on a device but can be used as system memory, the same as standard memory. This allows a flexible way to assign and manage system memory using memory devices.
As various...
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Daniel Lezcano (Linaro)19/09/2024, 10:50
The step wise governor is largely used by all mobile platforms. Those are more and more performant, so overheating very quickly. Given the speed of the temperature transitions, the step wise governor does not have enough time to apply the right cooling effect as it must go through several iteration to reach the temperature drop. Several iterations means hundreds of milliseconds. During this...
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Paolo Bonzini (Red Hat, Inc.)19/09/2024, 11:00
This session should group discussions on future extensions to guest_memfd, including:
- in-place replacement and userspace mmap of shared pages (https://lore.kernel.org/kvm/20240618-exclusive-gup-v1-0-30472a19c5d1@quicinc.com/)
- large folios
- hugetlbfs
- live migration aka send/receive (pages that are encrypted but accessible from userspace)
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Shiju Jose, Vandana Salve, Jonathan Cameron (Huawei Technologies R&D (UK))19/09/2024, 11:05
Beyond simple error reporting, the CXL specification defines many features related to RAS. Examples being Memory Patrol Scrub and ECS control + features such as PPR directed at the runtime repair of memory. Whilst part of our motivation for looking at this area was to support the CXL features, moves such as OCP RAS API suggest there will be future opportunity for reuse.
There is...
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Fuad Tabba (Google)19/09/2024, 11:10
This talk presents different proposals for supporting guest private memory in Android for Arm64 in the pKVM and the Gunyah hypervisors.
Confidential computing is gaining popularity, with hardware-based (Intel TDX, AMD SEV, Arm CCA) and software-based (pKVM, Gunyah) solutions. A common aspect is the ability to create a "protected" guest, whose data is neither inaccessible by other VMs nor by...
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Daniel Lezcano (Linaro)19/09/2024, 11:10
The userspace which has a complex logic to manage the thermal envelope of the platform is often platform specific because custom kernels export clumsily interfaces to act on PM. Therefore, the userspace is often unusable when we want to support mainline kernels. That leads to more work as there are multiple userspace implementation to achieve the same goal. The objective of the discussion /...
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Alejandro Lucero (AMD)19/09/2024, 12:00
As the author of a current RFC patchset under review for supporting a Type2 CXL device, it is worth to summarize what has been discussed so far, the current status of the patchset and also other tangential concerns like full privacy or CXL/PCIe slot resets and restoring CXL registers.
CXL.cache needs also to be discussed with the goal of defining a roadmap or at least first steps towards...
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Vishal Annapurve19/09/2024, 12:00
[guest_memfd][1] is a new feature providing a guest-first memory subsystem internal to KVM. Being internal to KVM opens guest_memfd up to virtualization-specific features, enhancements and optimizations.
A notable feature that guest_memfd currently lacks is 1G page support.
Here are some key benefits of 1G page support:
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Better performance due to
Increased hit rate in the TLB
Faster... -
Samuel Wu, Saravana Kannan19/09/2024, 12:00
As a community, we pay a lot of attention to the performance impact of the changes we land. Especially when it comes to areas like scheduler/cpufreq that are expected to have a significant impact on performance. This is possible because we have good benchmarks to quickly iterate over and check the impact of our patches.
However when it comes to checking the power/energy impact of our...
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John Groves (Micron)19/09/2024, 12:20
CXL version 3 supports shared memory that must remain separate from
system-RAM. This talk will cover the following:- How will CXL shared memory be managed?
- How do CXL Dynamic Capacity Devices fit into the shared memory picture?
- Specific challenges around cache coherency in both the hardware- and
software-managed coherency cases - Status update on famfs [1], which provides a...
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Saravana Kannan19/09/2024, 12:20
Optimizing suspend/resume time makes a significant difference for UX
and power savings. Especially for wearable devices which typically
have small CPUs and small batteries. This talk will point out all the
gaps we've found so far and what we could do to address them and some
of my TODOs to get there.- Optimizing global async suspend/resume
- Using runtime PM to avoid resume/suspend...
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Patrick Roy (Amazon UK)19/09/2024, 12:30
Since the discovery of Spectre and Meltdown in 2018, transient execution attacks are being discovered regularly, both in old and new hardware. Mitigation involves applying specific patches for each vulnerability, and is often costly in terms of performance, leading to cloud computing providers to seek more general mitigations.
The majority of these attacks are based on the presence of a...
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Ulf Hansson (Linaro)19/09/2024, 12:40
On legacy platforms it's common to support suspend-to-ram (S2R), but not suspend-to-idle (S2I). In many cases, this seems to be because of some limitations in the FW that deals with CPU power-management.
For various reasons, we want to promote S2I in favor of S2R due to the benefit it provides, but it's not always possible to convince vendors to update their FW for legacy platforms.
In a...
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Davidlohr Bueso (Samsung Semiconductor)19/09/2024, 12:45
This talk will present 'libcxlmi', a CXL Management Interface utility library. It provides type definitions for CXL specification structures, enumerations and helper functions to construct, send and decode CCI commands and payloads over both in-band (Linux) and out-of-band (OoB) link, typically MCTP-based CCIs over I2C or VDM.
The objective of this presentation is both to cover the design...
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James Houghton (Google)19/09/2024, 13:00
Problem: traditional implementation of post-copy live migration
The key challenge with post-copy live migration is intercepting accesses to particular pages of guest memory. Today, the only way to do this is to use userfaultfd, an mm feature that intercepts page faults (and other events). KVM, after translating a GFN to an HVA, will call GUP to translate the HVA to an HPA, thereby...
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Adam Manzanares, Viacheslav Dubeyko19/09/2024, 13:05
Benchmarking and efficiency estimation of CXL infrastructure is a crucial task for the whole CXL ecosystem. Which tool(s) can be used and how can we execute such benchmarking? Potentially, a benchmarking tool could simulate the target use-case (for example, huge relational database, in-memory database, huge social network, ML model training, Virtual Machine use-case, HPC use-case, and so on)....
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19/09/2024, 15:00
The Complex Camera Summit will be held just before Plumbers. For a whole day Vendors, Distros and Kernel Maintainers will have discuss the future of Complex Cameras in Linux, covering kernel APIs and userspace camera stacks.
During this presentation we will report the conclusions of that meeting to the rest of the community, gather feedback and discuss open questions.
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Pavel Tikhomirov (Virtuozzo)19/09/2024, 15:00
Unsolved CRIU problems.
1) Restoring complex process trees.
Processes can not enter into pre-existing process-session (sid), sessions can
only be inherited. (Same for process-groups (pgid) in nested pid namespaces.)Probable solution 1 - CABA:
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The idea was to save as much of the... -
Mr Benno Bielmeier (OTH Regensburg)19/09/2024, 15:00
Ensuring temporal correctness of real-time systems is challenging.
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The level of difficulty is determined by the complexity of hardware, software, and their interaction.
Real-time analysis on modern complex hardware platforms with modern complex software ecosystems, such as the Linux kernel with its userland, is hard or almost impossible with traditional methods like formal verification or... -
ATISH PATRA (Rivos), Palmer Dabbelt (Google)19/09/2024, 15:00
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19/09/2024, 15:05
Unified discovery is bad and should stay out of the kernel. I'm just going to have a single slide saying that.
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Radostin Stoyanov (Red Hat)19/09/2024, 15:20
Container checkpointing has recently been enabled in orchestration platforms like Kubernetes, where the smallest deployable unit is a Pod (a group of containers). However, these platforms are often used to deploy distributed applications running across multiple nodes, which presents a new challenge: How to create consistent global checkpoints of distributed applications running in multiple...
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Jan Kiszka (Siemens)19/09/2024, 15:22
Did you ever run into a real-time application that implicitly did a malloc in its critical code path? Or used the wrong lock type? Or did you even wrote it yourself? Wouldn't it be nice to get an earlier warning about such mistakes? Dual kernels like Xenomai provide such a feature, not perfectly, but way better than "native" RT Preempt can currently provide. And if you as users of Xenomai why...
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19/09/2024, 15:30
Allocating shared buffers between disparate hardware devices remains a significant challenge in modern systems. The diverse constraints of each device make it difficult to find allocation strategies that are both efficient and universally compatible. Current solutions often rely on ad-hoc workarounds and duct-tape.
This session aims to foster discussion on best practices for efficient...
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19/09/2024, 15:30
RISC-V Linux goes out of its way to consider overlapping-ISA heterogeneous multiprocessing when managing extensions. Let's review and discuss the current extension support to ensure there aren't gaps nor unnecessary burdens.
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Stéphane Graber (Zabbly)19/09/2024, 15:35
Containers are a user space fiction, there is no single container concept within the Linux kernel and what set of components constitutes a container isn't something we expect everyone to agree on any time soon (if ever).
That said, we've seen many ask for ways to easily figure out whether a process belongs to a container, if so, which one, who/what's responsible for it, ...
Some of the...
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John Kacur19/09/2024, 15:44
rteval is a tool to help measure real-time latency
It does this by running a measurement module such as cyclictest that both measures latency and simulates a real-time application, while also running load modules that simulate non-realtime applicationsRecently rteval has been undergoing a lot of development. These developments will improve the ability to measure and discover sources of...
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Aleksandr Mikhalitsyn (Canonical)19/09/2024, 15:50
This talk is about a problem of integration between the concept of an "isolated" ([1], [2], [3], [4]) user namespace and cgroup-v2 delegation model.
The biggest challenge here is that cgroup delegation is based on cgroupfs inodes ownership and cgroupfs superblock is shared between all containers which makes it impossible to deal with cgroupfs as with any other containerized filesystem like...
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19/09/2024, 16:00
Vendor Passthrough mechanisms enable direct communication between userspace and hardware devices, fully or partly bypassing traditional kernel software stacks. This approach has found applications in various subsystems, such as testing new protocols (e.g. NVMe Passthrough), debugging hardware, and implementing user-space drivers (e.g. DPDK). Some subsystems have set stricter rules governing...
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19/09/2024, 16:00
The upcoming series of ftrace code patching reduces the reach of each patch-site to a +/- 2KB range. This might be the unavoidable option we must take, as we move on to wave
Go to contribution pagestop_machine()away, support preemption, and maintain an acceptable code size. Thus, we are going to focus our discussions on what options are there for us to support direct calls and various ftrace optimizations.... -
Leonardo Bras Soares Passos (Red Hat)19/09/2024, 16:06
Some kernel code implement a parallel programming strategy
that grabs local_locks() for most of the work, and then use schedule_work_on(cpu) when some rare remote operations are needed. This is quite efficient for throughput, since it keeps cacheline mostly local and avoid locks in non-RT kernels, paying the price when you need to touch a remote CPU.On the other hand, that's quite bad...
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Aleksa Sarai (SUSE LLC)19/09/2024, 16:10
With the introduction of extensible-struct syscalls such as
Go to contribution pageopenat2andclone3, the inability to usefully filter syscalls with pointer arguments makes it harder for various programs to make use of newer kernel features because of both default container and self-hardening seccomp profiles. The inability for systemd and other system utilities to useRESOLVE_IN_ROOTand relatedopenat2... -
Leonardo Bras Soares Passos (Red Hat)19/09/2024, 16:28
In the mission of reducing latency in KVM guests, we have seen a lot of missed deadlines caused by RCU core invocation, often causing guest exit only to have a timer interrupt invoking rcu_core() on host and causing a task switch.
While looking to improve that, it was noticed that no RCU lock is held in guest context, and thus it's possible to report a quiescent state in guest exit,...
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Ariel Miculas19/09/2024, 17:00
PuzzleFS is a container filesystem designed to address the limitations of the existing OCI format. The main goals of the project are reduced duplication, reproducible image builds, direct mounting support and memory safety guarantees, some inspired by the OCIv2 brainstorm document.
Reduced...
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19/09/2024, 17:00
RISC-V IO Mapping Table (RIMT) is RISC-V specific ACPI table for providing the IOMMU information to the OS. This specification is currently in draft state and we have done PoC with qemu and linux. We would like to discuss linux changes required, the challenges and proposed solutions. The discussion would help greatly to freeze the specification.
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Valentin Schneider (Red Hat)19/09/2024, 17:02
CPU isolation allows us to shield a subset of CPUs from a lot of kernel interference, but not all of it. Activity on the housekeeping CPUs can and does trigger IPIs which can still end up targeting isolated CPUs. The main culprits here are static key updates and vunmap() + the resulting flush_tlb_kernel_range().
As discussed in previous editions, since these IPIs are only relevant to the...
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Tycho Andersen (Netflix)19/09/2024, 17:15
One question applications running in containers often ask is: how many CPUs do I have access to? They want to know, e.g., how many threads they can run in parallel for their threadpool size, or the number of thread-local memory arenas.
The kernel offers many endpoints to query this information. There is /proc/cpuinfo, /proc/stat, sched_getaffinity(), sysinfo(), the cpuset cgroup hierarchy's...
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John Stultz (Google)19/09/2024, 17:24
Proxy Execution has had a long history and has been worked on by many key scheduler developers and maintainers over the years. Because of this, when speaking at OSPM or Plumbers after picking up this work, I’ve often been very brief when covering the concept with the assumption that folks in the room often had more experience with it than I have.
However, I’ve found there are often a lot of...
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19/09/2024, 17:30
APLIC is optional in RISC-V. ACPI doesn't have any mechanism to directly support MSIs or GSI to MSI mapping without an wired IRQ to MSI bridge. This proposal takes an attempt to solve that problem.
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Michal Koutný (SUSE)19/09/2024, 17:35
Some users of systems with many cgroups may notice that things don't work as swiftly as with fewer cgroups. One part it is caused by simply greater amount of data that must be processed at higher hierarchy levels, another part is that more cgroups mean more frequent operations that affect the running system.
In this talk, I sum up changes from roughly past two years done to better cope with...
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Thadeu Lima de Souza Cascardo (Igalia)19/09/2024, 17:46
FIFO tasks may starve other non-RT tasks, which is mitigated by RT throttling.
Deadline servers have been introduced and are still under development as an alternative to mitigate and avoid starvation of non-RT tasks.
There is, however, the chance that some other FIFO tasks will be starved and that could lead to system deadlock.
I would like to open the discussion about the possibility...
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Kamalesh Babulal19/09/2024, 17:55
Enterprise users are likely one of the last holdovers still running cgroup
v1. As they continue to transition to cgroup v2, we would like to discuss
the deprecation (and potentially deletion) of cgroup v1.In 2022 [1], systemd proposed the removal of cgroup v1 support from systemd,
but the community wasn't (yet) ready.Work has already begun in the kernel to isolate cgroup v1 [2] in...
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19/09/2024, 18:00
We have a had discussions on enabling control flow integrity on riscv for user mode in past. Most of the discussions on that front have settled. In this talk we will do quick recap of user mode cfi support status and considerations with respect to vDSO management and focus on single label scheme. We will be discussing CPU assisted kernel control flow integrity for risc-v kernel as well. We...
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Sebastian Siewior19/09/2024, 18:08
An overview of the current status of PREEMPT_RT. What patches are still not merged upstream, which will be dropped. What are the current shortcomings, which are currently addressed and in what way.
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Mathieu Desnoyers (EfficiOS Inc.)19/09/2024, 18:15
- New machines with 512+ hardware threads (and thus logical CPUs) bring
interesting challenges for user-space per-CPU data structures due to
their large memory use. - The RSEQ per-memory-map concurrency IDs (upstreamed in Linux v6.3)
allow indexing user-space memory based on indexes derived from the
number of concurrently running threads, - I plan to apply the same concept to...
- New machines with 512+ hardware threads (and thus logical CPUs) bring
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Todd Kjos (Google)20/09/2024, 10:00
In pursuit of a stronger defense against kernel security issues, the Android ecosystem has been evolving since 2017 to more aggressively follow the upstream stable kernels. To support this evolution, the Android Common Kernel has been transformed from a reference kernel used primarily to cherry-pick features and security bug fixes into a binary release of a kernel that is kept up-to-date with...
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Claudio Carvalho, Stefano Garzarella (Red Hat), Tyler Fanelli (Red Hat)20/09/2024, 10:00
The integration of Secure Virtual Machine Service Module (SVSM) with virtual Trusted Platform Modules (vTPMs) is a critical component in establishing trust and security for confidential virtual machines (CVMs). This session delves into the latest advancements in SVSM vTPM technology, covering a wide range of topics from boot attestation to persistent storage and future development...
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Tim Bird (Sony)20/09/2024, 10:00
Benchmark test results are difficult to interpret in an automated fashion. They often require human interpretation to detect regressions because they depend on a number of variables, including configuration, cpu count, processor speed, storage speed, memory size, and other factors. Tim proposes a new system for managing benchmark data and interpretation in kselftest. It consist of 3 parts:...
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Serban Constantinescu (source.dev), Luca Weiss (Fairphone), Karim Yaghmour (Opersys inc.)20/09/2024, 10:20
The Android Open Source Project (AOSP) is an extremely attractive Linux-based stack for HMIs and all manner of richly-connected devices. Its ever expanding and industry-leading handset-grade feature-set, universally-known user experience and mostly permissive licensing make it a great fit for a large number of products. Despite all its benefits, however, keeping an AOSP-enabled device...
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Chuanxiao Dong, Jason Chen, Mr Jiewen Yao (Intel Corporation), Peter Fang, Vijay Dhanraj20/09/2024, 10:20
Intel's Trust Domain Extensions (TDX) coupled with Coconut-SVSM is emerging as a powerful combination for secure and efficient virtualization. This talk delves into the intricacies of Intel TD Partitioning, its role in running an SVSM, and its integration with a virtual Trusted Platform Module (vTPM).
We will provide a comprehensive overview of TD Partitioning, explaining its architecture,...
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David Gow (Google)20/09/2024, 10:30
There are several different testing frameworks for kernel and kernel-adjacent code, but KUnit is one of the most consistent and user-friendly. This means that KUnit is being used for things beyond its nominal scope of 'unit tests'. This includes stress tests, integration tests, and performance tests.
On the flipside, there are unit tests in the kernel tree for which KUnit's in-kernel nature...
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Mr Chris Simmonds20/09/2024, 10:40
AOSP is used in many different types of device, not just smart phones and tablets, but also digital advertising, white boards, building entry systems, and more. Consequently, there are a large number of AOSP developers, but where are they? It's like
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the Fermi Paradox, but for software engineers. Contrast this with the community around, for example, the Yocto Project, which is active and... -
Derek Miller (Arm Ltd)20/09/2024, 10:40
A discussion of the requirements and trade-offs that led to the planes feature of the Arm Confidential Compute Architecture, as well as a description of the system as specified. This discussion will lead to the requirements for and a description of our proposed specification for inter-plane communication on Arm platforms.
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Mr Dmitrii Merkurev (Google), Mr Ram Muthiah (Google)20/09/2024, 11:00
Context I'm going to provide:
- Android bootflow (current situation, problems, focus on bootloaders fragmentation which leads to upstream features adoption delays)
- Overview of the boot standards (UEFI, Coreboot, etc)
- GBL proposal (revealing early specs, focus on OEM requirements/customizations)
- How to try GBL with Cuttlefish
Potential discussion points:
1....
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Chris Oo (Microsoft)20/09/2024, 11:00
Guest operating systems generally require modifications, referred to as enlightenments, to run under different Confidential computing architectures such as AMD SEV-SNP or Intel TDX. To support unenlightened guests, a software component called a paravisor is required. The paravisor runs at a higher privilege level within the guest to provide the appropriate abstractions and security guarantees...
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Rae Moar20/09/2024, 11:00
Currently, kunit.py provides its own KTAP parser (in kunit_parser.py), specifically for KUnit use. While it can be used to parse KTAP from other sources, this is rarely done. This may be due to KUnit-specific features or difficulty accessing the parser. Unfortunately, this can lead to developers coding and maintaining other KTAP parsers that heavily overlap with this existing tooling.
We...
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Muhammad Usama Sardar (TU Dresden)20/09/2024, 11:15
Transport Layer Security (TLS) is a widely used protocol for secure channel establishment. However, it lacks an inherent mechanism for validating the security state of the workload and its platform. To address this, remote attestation can be integrated in TLS, which is named attested TLS. In this talk, we present a survey of the three approaches for this integration, namely pre-handshake...
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Prakash Gupta (Qualcomm)20/09/2024, 11:20
Kernel supports default cma and system dmabuf heaps. In order to support protected usecase, additional heap types needs to be supported.
There are quite a few downstream dmabuf heaps maintained by vendors to support protected usecase. There is need to provide generic framework, which will reduce fragmentation of such dmabuf heap types.
The proposed restricted dmabuf heaps will support...
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T.J. Mercier (Google - Android Kernel Team)20/09/2024, 12:00
This talk will cover the status of recent changes in Android and upstream related to memory control groups, planned work, and outstanding issues.
Here are some details:
Updates:
- memcg v2 can now be used in A15 with
PRODUCT_MEMCG_V2_FORCE_ENABLEDor vendor overrides of cgroups.json - Control of memcg activation depth is queued for A16 (Reduction in kernel...
- memcg v2 can now be used in A15 with
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Jinank Jain (Microsoft), Mr Muminul Islam (Microsoft)20/09/2024, 12:00
As cloud technologies continue to advance at a rapid pace, there arises a critical need to assess the performance disparities among various virtualization stacks. This presentation aims to shed light on the comparative performance, scalability, and efficiency of two prominent hypervisor technologies—KVM/QEMU and Linux as Root Partition for Microsoft Hyper-V with Cloud-Hypervisor as VMM —within...
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Tingxu Ren (University of Illinois at Urbana-Champaign), Wentao Zhang (University of Illinois Urbana-Champaign), Darko Marinov (University of Illinois at Urbana-Champaign), Jinghao Jia (University of Illinois Urbana-Champaign), Tianyin Xu (University of Illinois at Urbana-Champaign)20/09/2024, 12:00
We have been working on an LLVM-based toolchain for measuring test adequacy of existing kernel tests from test suites including KUnit [1], kselftest [2], LTP [3], test suites from RHEL [4] and more in KCIDB [5]. We measure different adequacy metrics including basic metrics statement coverage and branch coverage, and advanced metric Modified Condition/Decision Coverage (MC/DC) [6].
This talk...
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Juan Yescas, Mr Kalesh Singh20/09/2024, 12:20
Android's transition to 16kb page sizes necessitates a comprehensive overhaul of device components to ensure seamless compatibility and optimal performance. This presentation will delve into the critical modifications required across the entire software stack:
- Bootloader: We'll explore the necessary adjustments to the bootloader to accommodate the 16kb page size, ensuring a smooth...
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Alexey Kardashevskiy (AMD), Dan Williams (Intel Open Source Technology Center), Mr Jiewen Yao (Intel Corporation), Samuel Ortiz, Suzuki Kuruppassery Poulose (Arm Holdings Ltd)20/09/2024, 12:20
The secure and efficient transfer of data between confidential computing environments and the outside world is a critical challenge. This session brings together experts from different architectures to discuss the latest advancements in trusted I/O. We will explore the design principles, implementation details, and interoperability aspects of emerging standards such as RISC-V CoVE-IO, Arm CCA,...
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Nicolas Prado (Collabora)20/09/2024, 12:30
A large percentage of the functionality provided by the kernel to userspace
comes from the different devices in the system. For that reason, having a proper
common approach in mainline to test devices and detect regressions is of the
utmost importance for the kernel's reliability.Devices are exposed through a diverse set of interfaces (uAPIs) and fully
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testing them requires just as... -
Akilesh Kailash20/09/2024, 12:40
This presentation delves into the ongoing upstream work: ublk zero copy based io_uring effort:
https://lore.kernel.org/io-uring/06c5f635-b065-4ff1-9733-face599ddfe3@gmail.com/T/#m6c99306b44992ee8fc12ad4e9d7a28cd59e081bb
The talk will focus on:
1: Why ublk zero copy is required in Android and how it will be used. Will explore the use cases that necessitate the implementation of ublk...
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David Hartley (Qualcomm Germany GmbH)20/09/2024, 12:50
The PCIe TEE Device Interface Security Protocol (TDISP, aka TEE-I/O) specifies requirements for a TEE Security Manager (TSM) on the host and a Device Security Manager (DSM) on a PCIe device, including an on-chip Root Complex-integrated Endpoint (RCiEP). TDISP also specifies protocols between TSM and DSM to establish trust between a confidential VM and a PCIe device or function, secure the...
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Barry Song, Mr Chuanhua Han, Mr Hailong Liu, Kalesh Singh (Google), Yu Zhao (Google)20/09/2024, 13:00
OPPO has deployed ARM64 CONT-PTE-based large folios (mTHP) on millions of real phones and is committed to contributing the code to Linus' tree, GKI, and the open-source community.
This topic will primarily discuss the opportunities and challenges encountered by OPPO in memory allocation, memory reclamation, LRU, and mTHP compression/decompression in zsmalloc/zRAM during the deployment of...
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RAVI SAHITA (Rivos)20/09/2024, 13:00
This session will discuss the ongoing development of the RISC-V architecture for Confidential VM Extension (CoVE) and related CoVE-IO (for TEE-IO). The discussion will cover both the WIP ISA (CPU) and non-ISA (ABI, IOMMU and other platform aspects) extensions. The WIP ISA extensions will cover the proposed Smmtt (memory isolation) and related extensions for interrupts isolation, IO-MTT and...
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Helen Koike (Collabora), Ricardo Cañuelo20/09/2024, 13:00
CI systems can generate a big amount of test results, so processing and interacting with that data in a timely, efficient manner is paramount. At KernelCI, we are investing a lot into improving the quality of the test results through automatic post-processing, grouping and filtering to find common patterns and surface the most important test failures to the kernel community.
In this...
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Chris Porter (IBM Research), Claudio Carvalho, Daniele Buono (IBM), Niteesh Dubey (IBM), Tobin Feldman-Fitzthum (IBM)20/09/2024, 13:10
Trustee, formerly referred to as KBS, is a set of attestation and key management services for confidential workloads. In the past year the project has grown considerably, now supporting attestation of 8 different confidential platforms. This talk will briefly introduce the project and these updates but the main focus is ongoing work.
The talk will touch on the community's plan to support...
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Khasim Syed Mohammed20/09/2024, 15:00
Boot time plays an important role in defining the user experience of a product, the more time it takes in getting the device into action the quicker it is pulled out of the stands.
Linux & it’s stacks can be tweaked to boot as quickly as possible but the challenge is beyond just optimizing the flow – it gets into defining the use cases to go after – to – productizing these features and...
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Suren Baghdasaryan, Pasha Tatashin, Sourav Panda (Google)20/09/2024, 15:00
Memory allocation profiling infrastructure provides a low-overhead mechanism to make all kernel allocations in the system visible. This allows for monitoring memory usage, tracking hotspots, detecting leaks, and identifying regressions.
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Unlike previous discussions on the design of this technique, we will now focus on the changes since it was incorporated into the upstream kernel, planned... -
Petr Tesařík20/09/2024, 15:15
For decades, Linux memory management has been mostly focused on the needs of
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user space and generic kernel-space users (memory control groups, transparent
huge pages, compression). Other big changes are good for maintenance and/or
debugging (removal of DISCONTIGMEM, compaction, kmemleak, folios, removal of
redundant slab-style allocators and many other). Little has been done for... -
Laura Nao (Collabora)20/09/2024, 15:30
The Linux kernel currently lacks common upstream terminology for measuring
boot time. Although tools like ftrace are available to trace boot-time
events, there is no standardized approach (and upstream kselftest!) to
measure and identify slowdowns during different stages of the boot process.In this session, we will explore how to leverage existing tracing tools to
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monitor key events in... -
SeongJae Park20/09/2024, 15:30
There are two hopes for Linux kernel. Some people hope the kernel to just works without users' intervention. Meanwhile, some people hope the kernel be extensible so that the users can flexibly control the kernel with their proprietary information.
DAMON is designed and planned to convince the two parties. Also, because DAMON is a part of memory management subsystem, it should also...
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Liam Howlett (Oracle), Lorenzo Stoakes (Oracle)20/09/2024, 15:45
vma guards are inserted at the start and/or end of vmas to detect out-of-bound reads or writes. Currently these guards are represented by an allocated vma even though almost all the information in the vma is not used. Sometimes these guards are so numerous that they represent close to half of the vmas used in a system. Such a large number of underutilized objects represents a potential for...
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Tim Bird (Sony)20/09/2024, 16:00
This session is intended to present and discuss 3 different technology areas surrounding boot-time reduction for Linux systems: 1) boot time markers, 2) boot phases, and 3) profile-guided boot-time optimizations. Boot-time markers is a proposed set of well-define measurement points in the Linux boot process, used for testing improvements and regressions in boot time. "Boot phases" refers to...
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Rik van Riel (Facebook)20/09/2024, 16:00
Conventional wisdom has held that madvise overhead has been mostly the syscall overhead. However, profiling shows this not to be the case.
Even on a medium sized 1 socket system, about half the CPU time spent in MADV_DONTNEED is spent flushing the TLB, and that is just in the calling CPU. Add in handling of the TLB flush IPIs on the other CPUs, and 90-95% of the MADV_DONTNEED overhead is...
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Kundan Kumar (Samsung Semiconductor India Research)20/09/2024, 16:15
Direct and passthrough IO involves mapping user space memory into the kernel. At present, this memory is mapped as an array of pages. Using 4K pages for mapping results in additional overhead due to per-page memory pinning, unpinning, and calculations. Switching to a large folio-based mapping will reduce this overhead.
As part of this proposal, the current GUP implementation needs to be...
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Stefan Schmidt20/09/2024, 17:00
This session will discuss the current problems faced for the linux-wpan/ieee802154 subsystem. We will have small problem statements before discussion on ongoing work and clarification of requirements:
- IEEE 802.15.4 SubGHz phy layer support: current status and improvements on Linux (and hopefully Zephyr)
- UWB phy and driver support, needed mac802154 enhancements
- Requirement gathering...
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Juan Yescas, Kalesh Singh (Google)20/09/2024, 17:00
During the transition to a 16kb page size system, numerous instances were found where the kernel or userspace relied on the assumption of PAGE_SIZE == 4096. While many functional issues have been resolved, some inherent challenges persist, along with opportunities for optimization in systems with larger page sizes.
This work investigates the following key challenges and potential areas of...
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Chris Li (Google), Kairui Song (Tencent)20/09/2024, 17:15
The swap system original only need to handle 4K and THP size swap. When mTHP introduce more size option for swap, it also bring new challenge of the swap fragmentation. The swap sub system will need some change for the new allocation requirement.
The presentation will propose some swap allocator approaches to address the mthp swap fragmentation. Some of the patch series already send to the...
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Marc Kleine-Budde (Pengutronix), Oleksij Rempel (Pengutronix)20/09/2024, 17:25
Marc (Linux kernel CAN subsystem maintainer) and Oleksij (Linux kernel J1939 maintainer) will give an overview of current best practices for the Linux CAN subsystem and J1939 stack.
They will address high latencies in the RX path, presenting a two-step approach to avoid buffer overflows and out-of-order reception using the RX-Offload helper.
Modern CAN controllers provide RX and...
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Barry Song, Mr Chuanhua Han, Mr Tangquan Zheng20/09/2024, 17:30
In addition to the work by Chris Li and Ryan Roberts on optimizing mTHP swap-out slot allocation [1][2], we at OPPO have several patchsets focused on mTHP swap-in [3][4] and enhancing zsmalloc/zRAM [5] to save and restore compressed mTHP.
Without mTHP swap-in, mTHP is a one-way ticket: once swapped out, they cannot revert to mTHP. With mTHP swap-in, we make mTHP bidirectional and gain the...
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Luca Ceresoli (Bootlin), Hervé Codina20/09/2024, 17:45
New embedded products are being developed by the industry having add-on boards that can be hot-plugged to the main board to extend features, and do so using busses not natively hot-pluggable and discoverable such as USB or PCI. Instead they use busses that are traditionally not removable such as I²C, SPI, and even more complex ones such as MIPI DSI.
Currently Linux is unable to handle such...
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Axel Rasmussen (Google), Guru Anbalagane (Google), Wei Xu (Google), Yuanchu Xie (Google)20/09/2024, 17:45
- Adopting MGLRU in Google's production kernel
- Predicable DRAM scheduling based on working set
- Leveraging page table scanning for NUMA and CXL
- Path for MGLRU to become the default
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Yu Zhao (Google)20/09/2024, 18:00
TAO is an umbrella project aiming at a better economy of physical contiguity viewed as a valuable resource. A few examples are:
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1. A multi-tenant system can have guaranteed THP coverage while hosting abusers/misusers of the resource.
2. Abusers/misusers, e.g., workloads excessively requesting and then splitting THPs, should be punished if necessary.
3. Good citizens should be awarded with,... -
Schuyler Patton (Texas Instruments - Embedded Processing)20/09/2024, 18:10
In Linux based IOT embedded applications there has always been this ongoing desire to attach MCUs (Micro-Controller Unit) to MPUs (Micro-Processor Unit) running Linux. The usual reason is that the MCU is able to handle low latency data processing more efficiently then the higher-level functioning MPU. The MCU might also add a missing peripheral on the MPU that is more system cost efficient....
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Yu Zhao (Google)20/09/2024, 18:15
There are three types of zones:
1. The first four zones partition the physical address space of CPU memory.
2. The device zone provides interoperability between CPU and device memory.
3. The movable zone commonly represents a memory allocation policy.Though originally designed for memory hot removal, the movable zone is instead widely used for other purposes, e.g., CMA and kdump kernel,...
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Amit Pundir, Fuad Tabba (Google), John Stultz (Google), Karim Yaghmour (Opersys inc.), Lukasz Luba, Sumit Semwal (Linaro)
CFP closes on July 5th.
The Android Micro Conference brings the upstream community and Android systems developers together to discuss issues and changes to the Android platform and their dependencies and interactions with the Linux kernel, allowing for collaboration on solutions for upstream.Some highlights of progress made since last year’s MC:
- For fw_devlink, got...
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Amit Pundir, Fuad Tabba (Google), John Stultz (Google), Karim Yaghmour (Opersys inc.), Lukasz Luba, Sumit Semwal (Linaro)
CFP closes on July 5th.
The Android Micro Conference brings the upstream community and Android systems developers together to discuss issues and changes to the Android platform and their dependencies and interactions with the Linux kernel, allowing for collaboration on solutions for upstream.Some highlights of progress made since last year’s MC:
- For fw_devlink, got...
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Josef Holzmayr, Philip Balister (OpenEmbedded)
CFP closes on July 5th.
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At Plumbers 2023 we held a build systems microconference to provide a place for people interested in build Linux Distributions to discuss the common problems they face. Based on the success of the 2023 microconference, we would like to have another microconference in Vienna. Last year, people discussed, supply chain security, kernel management, user api... -
Josef Holzmayr, Philip Balister (OpenEmbedded)
CFP closes on July 5th.
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At Plumbers 2023 we held a build systems microconference to provide a place for people interested in build Linux Distributions to discuss the common problems they face. Based on the success of the 2023 microconference, we would like to have another microconference in Vienna. Last year, people discussed, supply chain security, kernel management, user api... -
CFP closes on July 15th.
The camera hardware landscape has undergone a dramatic transformation, moving from simple frame producers to highly configurable and programmable systems. Unfortunately, open-source camera software has struggled to keep pace, creating a bottleneck that hinders innovation and limits the potential of modern camera technology.
This microconference will bring...
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CFP closes on July 15th.
The camera hardware landscape has undergone a dramatic transformation, moving from simple frame producers to highly configurable and programmable systems. Unfortunately, open-source camera software has struggled to keep pace, creating a bottleneck that hinders innovation and limits the potential of modern camera technology.
This microconference will bring...
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Adam Manzanares (Samsung Electronics), Dan Williams (Intel Open Source Technology Center), Davidlohr Bueso (Samsung Semiconductor), Jonathan Cameron (Huawei Technologies R&D (UK))
CFP closes on July 5th.
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Compute Express Link is a cache coherent fabric that has been gaining momentum in the industry. Whilst the ecosystem is still catching up with CXL 3.0 and earlier features, CXL 3.1 launched just after the 2023 CXL uconf, bringing yet more challenges for the community (temporal sharing, advanced RAS features). There also has been controversy and confusion in the... -
Adam Manzanares (Samsung Electronics), Dan Williams (Intel Open Source Technology Center), Davidlohr Bueso (Samsung Semiconductor), Jonathan Cameron (Huawei Technologies R&D (UK))
CFP closes on July 5th.
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Compute Express Link is a cache coherent fabric that has been gaining momentum in the industry. Whilst the ecosystem is still catching up with CXL 3.0 and earlier features, CXL 3.1 launched just after the 2023 CXL uconf, bringing yet more challenges for the community (temporal sharing, advanced RAS features). There also has been controversy and confusion in the... -
Dhaval Giani, Joerg Roedel (SUSE)
CFP closes on July 15th.
Confidential Computing microconferences in the past years brought together developers working secure execution features in hypervisors, firmware, Linux Kernel, over low-level user space up to container runtimes. A broad range of topics were discussed ranging from entablement for hardware features up to generic attestation workflows.In the past year - guest...
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Dhaval Giani, Joerg Roedel (SUSE)
CFP closes on July 15th.
Confidential Computing microconferences in the past years brought together developers working secure execution features in hypervisors, firmware, Linux Kernel, over low-level user space up to container runtimes. A broad range of topics were discussed ranging from entablement for hardware features up to generic attestation workflows.In the past year - guest...
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Mr Christian Brauner, Mike Rapoport (IBM), Stéphane Graber (Zabbly)
CFP closes on July 15th.
The Containers and Checkpoint/Restore micro-conference focuses on both userspace and kernel related work. The micro-conference targets the wider container ecosystem ideally with participants from all major container runtimes as well as init system developers.The microconference will be discussing recent advancements in container technologies with some of the...
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Mr Christian Brauner, Mike Rapoport (IBM), Stéphane Graber (Zabbly)
CFP closes on July 15th.
The Containers and Checkpoint/Restore micro-conference focuses on both userspace and kernel related work. The micro-conference targets the wider container ecosystem ideally with participants from all major container runtimes as well as init system developers.The microconference will be discussing recent advancements in container technologies with some of the...
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André Almeida (Igalia)
CFP closes on July 15th.
The Graphics & DRM Microconference welcomes the community to discuss topics around the Linux graphics stack and the DRM subsystem, with the goal of solving long standing and complex problems together.The MC CfP is open to all proposals related to graphics, including the following potential topics:
- Rust and DRM
- Color management and HDR
- Automated...
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André Almeida (Igalia)
CFP closes on July 15th.
The Graphics & DRM Microconference welcomes the community to discuss topics around the Linux graphics stack and the DRM subsystem, with the goal of solving long standing and complex problems together.The MC CfP is open to all proposals related to graphics, including the following potential topics:
- Rust and DRM
- Color management and HDR
- Automated...
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Jan Lübbe (Pengutronix), Mr Stefan Schmidt, Tim Bird (Sony)
CFP closes on July 5th.
The IoT and Embedded Micro-conference is a forum for developers to discuss all things IoT and Embedded. Topics include tools, telemetry, device drivers, protocols and standards in not only the Linux kernel but also Real-Time Operating Systems such as Zephyr.Current Problems that require attention (stakeholders):
- IEEE 802.15.4 SubGHz improvement areas in...
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Jan Lübbe (Pengutronix), Mr Stefan Schmidt, Tim Bird (Sony)
CFP closes on July 5th.
The IoT and Embedded Micro-conference is a forum for developers to discuss all things IoT and Embedded. Topics include tools, telemetry, device drivers, protocols and standards in not only the Linux kernel but also Real-Time Operating Systems such as Zephyr.Current Problems that require attention (stakeholders):
- IEEE 802.15.4 SubGHz improvement areas in...
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CFP closes on July 5th.
Memory management has become exciting again. Some controversial subjects which might merit discussion:- Should we add memory policy zones?
- How far should we go to support CXL?
- How do we handle page allocation in a memdesc world?
- Should we switch the slab allocator from partial slabs to sheaves?
- Can we get rid of non-compound multi-page...
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CFP closes on July 5th.
Memory management has become exciting again. Some controversial subjects which might merit discussion:- Should we add memory policy zones?
- How far should we go to support CXL?
- How do we handle page allocation in a memdesc world?
- Should we switch the slab allocator from partial slabs to sheaves?
- Can we get rid of non-compound multi-page...
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Guillaume Tucker, Sasha Levin, Shuah Khan (The Linux Foundation)
CFP closes on July 14th.
The Kernel Testing & Dependability Micro-Conference (a.k.a. Testing MC) focuses on advancing the current state of testing of the Linux Kernel and its related infrastructure.
Building upon the momentum from previous years, the Testing MC's main purpose is to promote collaboration between all communities and individuals involved with kernel testing and...
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Guillaume Tucker, Sasha Levin, Shuah Khan (The Linux Foundation)
CFP closes on July 14th.
The Kernel Testing & Dependability Micro-Conference (a.k.a. Testing MC) focuses on advancing the current state of testing of the Linux Kernel and its related infrastructure.
Building upon the momentum from previous years, the Testing MC's main purpose is to promote collaboration between all communities and individuals involved with kernel testing and...
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CFP closes on July 5th.
The focus of this microconference will be on topics related to the APIs and interfaces sitting at the boundary between the kernel and init systems/system management layers, with a special attention directed towards current pain points and omissions.For example, issues around the current way initrd are loaded and set up between the bootloader and the kernel as...
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CFP closes on July 5th.
The focus of this microconference will be on topics related to the APIs and interfaces sitting at the boundary between the kernel and init systems/system management layers, with a special attention directed towards current pain points and omissions.For example, issues around the current way initrd are loaded and set up between the bootloader and the kernel as...
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Paolo Bonzini (Red Hat), Paolo Bonzini (Red Hat, Inc.), Sean Christopherson (Google)
CFP closes on July 12th.
KVM (Kernel-based Virtual Machine) enables the use of hardware features to
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improve the efficiency, performance, and security of virtual machines (VMs)
created and managed by userspace. KVM was originally developed to accelerate
VMs running a traditional kernel and operating system, in a world where the
host kernel and userspace are part of the... -
Paolo Bonzini (Red Hat), Paolo Bonzini (Red Hat, Inc.), Sean Christopherson (Google)
CFP closes on July 12th.
KVM (Kernel-based Virtual Machine) enables the use of hardware features to
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improve the efficiency, performance, and security of virtual machines (VMs)
created and managed by userspace. KVM was originally developed to accelerate
VMs running a traditional kernel and operating system, in a world where the
host kernel and userspace are part of the... -
CFP closes on July 7th.
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The Power Management and Thermal Control microconference is about all things related to saving energy and managing heat. Among other things, we care about thermal control infrastructure, CPU and device power-management mechanisms, energy models, and power capping. In particular, we are interested in improving and extending thermal control support in the Linux... -
CFP closes on July 7th.
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The Power Management and Thermal Control microconference is about all things related to saving energy and managing heat. Among other things, we care about thermal control infrastructure, CPU and device power-management mechanisms, energy models, and power capping. In particular, we are interested in improving and extending thermal control support in the Linux... -
Dhruva Gole
In the TI K3 AM62 Family of devices the hardware supports multiple Low Power Modes that retain context in the DRAM. However, Linux doesn't have direct awareness or any solid framework that allows a user to select a particular system-wide low power mode. This makes it challenging for any user to select which low power mode to enter in the SoC.
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After discussions with the community and with... -
Dhruva Gole
In the TI K3 AM62 Family of devices the hardware supports multiple Low Power Modes that retain context in the DRAM. However, Linux doesn't have direct awareness or any solid framework that allows a user to select a particular system-wide low power mode. This makes it challenging for any user to select which low power mode to enter in the SoC.
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After discussions with the community and with... -
Daniel Bristot de Oliveira (Red Hat, Inc.), Frederic Weisbecker (Suse), Juri Lelli (Red Hat), Sebastian Siewior
CFP closes on July 12th.
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The real-time community around Linux has been responsible for important changes in the kernel over the last few decades. Preemptive mode, high-resolution timers, threaded IRQs, sleeping locks, tracing, deadline scheduling, and formal tracing analysis are integral parts of the kernel rooted in real-time efforts, mostly from the PREEMPT_RT patch set. The real-time... -
Daniel Bristot de Oliveira (Red Hat, Inc.), Frederic Weisbecker (Suse), Juri Lelli (Red Hat), Sebastian Siewior
CFP closes on July 12th.
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The real-time community around Linux has been responsible for important changes in the kernel over the last few decades. Preemptive mode, high-resolution timers, threaded IRQs, sleeping locks, tracing, deadline scheduling, and formal tracing analysis are integral parts of the kernel rooted in real-time efforts, mostly from the PREEMPT_RT patch set. The real-time... -
ATISH PATRA (Rivos), Palmer Dabbelt (Google)
CFP closes on July 15th.
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We are excited to propose the next edition of the RISC-V micro conference to be held during the Plumbers Conference in 2024. This event has consistently served as a pivotal gathering for developers, enthusiasts, and stakeholders in the RISC-V ecosystem, especially those focused on its integration and evolution within the Linux environment. Broadly speaking... -
ATISH PATRA (Rivos), Palmer Dabbelt (Google)
CFP closes on July 15th.
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We are excited to propose the next edition of the RISC-V micro conference to be held during the Plumbers Conference in 2024. This event has consistently served as a pivotal gathering for developers, enthusiasts, and stakeholders in the RISC-V ecosystem, especially those focused on its integration and evolution within the Linux environment. Broadly speaking... -
Miguel Ojeda, Wedson Almeida Filho
CFP closes on July 14th.
Rust is a systems programming language that is making great strides in becoming the next big one in the domain. Rust for Linux is the project adding support for the Rust language to the Linux kernel.
Rust has a key property that makes it very interesting as the second language in the kernel: it guarantees no undefined behavior...
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Miguel Ojeda, Wedson Almeida Filho
CFP closes on July 14th.
Rust is a systems programming language that is making great strides in becoming the next big one in the domain. Rust for Linux is the project adding support for the Rust language to the Linux kernel.
Rust has a key property that makes it very interesting as the second language in the kernel: it guarantees no undefined behavior...
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Kate Stewart (Linux Foundation), Philipp Ahmann (Robert Bosch GmbH)
CFP closes on July 10th.
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As Linux is increasingly deployed in systems with varying criticality constraints, distro providers are being expected to ensure that security fixes in their offerings do not introduce regressions for customer products that have safety considerations. The key question arises: How can they establish consistent linkage between code, tests, and the requirements... -
Kate Stewart (Linux Foundation), Philipp Ahmann (Robert Bosch GmbH)
CFP closes on July 10th.
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As Linux is increasingly deployed in systems with varying criticality constraints, distro providers are being expected to ensure that security fixes in their offerings do not introduce regressions for customer products that have safety considerations. The key question arises: How can they establish consistent linkage between code, tests, and the requirements... -
Daniel Bristot de Oliveira (Red Hat, Inc.), Juri Lelli (Red Hat), Steven Rostedt, Vincent Guittot (Linaro)
CFP closes on July 12th.
The scheduler is at the core of Linux performance. With different topologies and workloads, giving the user the best experience possible is challenging, from low latency to high throughput and from small power-constrained devices to HPC.
The following accomplishments have been made as a result of last year’s micro-conference:- Progress on proxy...
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Daniel Bristot de Oliveira (Red Hat, Inc.), Juri Lelli (Red Hat), Steven Rostedt, Vincent Guittot (Linaro)
CFP closes on July 12th.
The scheduler is at the core of Linux performance. With different topologies and workloads, giving the user the best experience possible is challenging, from low latency to high throughput and from small power-constrained devices to HPC.
The following accomplishments have been made as a result of last year’s micro-conference:- Progress on proxy...
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Andrea Righi (NVIDIA), Changwoo Min (Igalia), David Vernet (Meta), Mr Giovanni Gherdovich (SUSE), Mrs Himadri Chhaya-Shailesh (Inria-Paris), Mr Peter Jung (CachyOS), Mr Piotr Górski (CachyOS)
Overview
[sched_ext][1] is a Linux kernel feature which enables implementing host-wide, safe kernel thread schedulers in BPF, and dynamically loading them at runtime. sched_ext enables safe and rapid iterations of scheduler implementations, thus radically widening the scope of scheduling strategies that can be experimented with and deployed, even in massive and complex production...
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Andrea Righi (NVIDIA), Changwoo Min (Igalia), David Vernet (Meta), Mr Giovanni Gherdovich (SUSE), Mrs Himadri Chhaya-Shailesh (Inria-Paris), Mr Peter Jung (CachyOS), Mr Piotr Górski (CachyOS)
Overview
[sched_ext][1] is a Linux kernel feature which enables implementing host-wide, safe kernel thread schedulers in BPF, and dynamically loading them at runtime. sched_ext enables safe and rapid iterations of scheduler implementations, thus radically widening the scope of scheduling strategies that can be experimented with and deployed, even in massive and complex production...
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CFP closes on July 14th
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The System Boot and Security Microconference has been a critical platform for enthusiasts and professionals working on firmware, bootloaders, system boot, and security. This year, the conference focuses on the challenges that arise when upstreaming boot process improvements to Linux kernel. Cryptography, which is an ever evolving field, poses unique demands on... -
CFP closes on July 14th
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The System Boot and Security Microconference has been a critical platform for enthusiasts and professionals working on firmware, bootloaders, system boot, and security. This year, the conference focuses on the challenges that arise when upstreaming boot process improvements to Linux kernel. Cryptography, which is an ever evolving field, poses unique demands on... -
How did TPM2 began its journey in Linux kernel and where it is heading? Why is TPM2 important for Linux? TPM2 is more like a protocol or contract for hardware cryptography than just a chip. And it still has a legit place despite Trusted Execution Environments (TEEs) and confidential computing up-rise.
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How did TPM2 began its journey in Linux kernel and where it is heading? Why is TPM2 important for Linux? TPM2 is more like a protocol or contract for hardware cryptography than just a chip. And it still has a legit place despite Trusted Execution Environments (TEEs) and confidential computing up-rise.
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The [PCI interconnect][1] specification, the devices that implement it, and the system IOMMUs that provide memory and access control to them are nowadays a de-facto standard for connecting high-speed components, incorporating more and more features such as:
- Address Translation Service (ATS)/Page Request Interface (PRI)
- [Single-root I/O Virtualization (SR-IOV)][2]/Process Address Space...
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The [PCI interconnect][1] specification, the devices that implement it, and the system IOMMUs that provide memory and access control to them are nowadays a de-facto standard for connecting high-speed components, incorporating more and more features such as:
- Address Translation Service (ATS)/Page Request Interface (PRI)
- [Single-root I/O Virtualization (SR-IOV)][2]/Process Address Space...
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Wei Huang
PCIe standard TLP processing hints (TPH) allow steering tags (STs) to be attached to PCIe TLP headers to facilitate optimized processing of DMA write requests that target memory space. New AMD hardware, by leveraging TPH, will support smart data cache injection where DMA data will be prefetched into L2 cache of target CCXs rather than DRAM. These new technologies can potentially improve DMA...
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Wei Huang
PCIe standard TLP processing hints (TPH) allow steering tags (STs) to be attached to PCIe TLP headers to facilitate optimized processing of DMA write requests that target memory space. New AMD hardware, by leveraging TPH, will support smart data cache injection where DMA data will be prefetched into L2 cache of target CCXs rather than DRAM. These new technologies can potentially improve DMA...
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CFP closes on July 12th.
X86-focused material has historically been spread out at Plumbers. This will be an x86-focused microconference. Broadly speaking, anything that might affect arch/x86 is on topic, except where there may be a more focused discussion occurring, like around Confidential Computing or KVM.This microconference would look at how to address new x86 processor features...
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CFP closes on July 12th.
X86-focused material has historically been spread out at Plumbers. This will be an x86-focused microconference. Broadly speaking, anything that might affect arch/x86 is on topic, except where there may be a more focused discussion occurring, like around Confidential Computing or KVM.This microconference would look at how to address new x86 processor features...
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CFP closes on July 12th.
Zoned Storage Devices MC - SMR HDDs, ZNS SSDs, Zoned mobile flash (UFS)We making good progress with zoned storage support in Linux, improving and adding support throughout the stack from low level drivers to file systems, user space tooling and cloud infrastructure.
Since the last LPC MC on the topic,...
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CFP closes on July 12th.
Zoned Storage Devices MC - SMR HDDs, ZNS SSDs, Zoned mobile flash (UFS)We making good progress with zoned storage support in Linux, improving and adding support throughout the stack from low level drivers to file systems, user space tooling and cloud infrastructure.
Since the last LPC MC on the topic,...
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