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...
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...
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...
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.
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 ).
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...
In this talk we present our efforts on implementing a safe Rust API for the hrtimer subsystem. 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 workqueue Rust abstractions, and other challenges in defining an ergonomic and safe API.
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...
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).
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...
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...
The organizers introduce themselves and set expectations
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...
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
around (DRM CI, MediaCI, KCI-Gitlab, CKI, Intel XE, etc.), depicting the
large overlaps but also the...
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....
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.
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?
The C library plays a crucial role in this. Having the flexibility to choose one
C...
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...
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.
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,...
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...
This is a open slot that can be used if the MC contributors wants more time to work together in some topic
A brief hello from the CXL uconf organizers.
The usual collection of small administrative elements.
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...
CXL - Dynamic Capacity Devices (DCD)
CXL introduced Dynamic capacity device support in CXL 3.0 and 3.1. The feature
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...
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...
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...
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...
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...
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)....
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:
The idea was to save as much of the...
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...
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...
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...
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...
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....
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...
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...
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
testing them requires just as...
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...
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...
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...
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...
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....
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...
CFP closes on July 5th.
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 5th.
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...
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...
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...
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...
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...
CFP closes on July 12th.
KVM (Kernel-based Virtual Machine) enables the use of hardware features to
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...
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...
CFP closes on July 12th.
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...
CFP closes on July 15th.
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...
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...
CFP closes on July 10th.
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...
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...
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...
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,...