Continuing in the same direction as last year, this year's Android microconference will be an opportunity to foster collaboration between the Android and Linux kernel communities. Discussions will be centered on the goal of ensuring that both the Android and Linux development moves in a lockstep fashion going forward.
- GKI experience (Elliot Berman)
- Technical debt (Matthias Männich)
- Hermetic builds with Bazel (Matthias Männich)
- STG for ABI monitoring (Giuliano Procida)
- fw_devlink and parallelization updates (Saravana Kannan)
- Virtualization in Android (David Brazdil, Serban Constantinescu)
- Cuttlefish and Kernel Dev (Ram Muthiah)
- eBPF-based FUSE (Paul Lawrence)
- EROFS as a replacement for EXT4 and Squashfs (David Anderson)
- MGLRU results on Android (Kalesh Singh)
- io_uring in Android (Akilesh Kailash)
- (Impact of) Recent CPU topology changes (Dietmar Eggemann, Ionela Voinescu)
- Dynamic Energy Model to handle leakage power (Lukasz Luba)
Accomplishments since the last Android MC:
- fw_devlink: Fixed the correctness of sync_state() callbacks when simple-bus devices are involved
- Implemented a prototype for the cgroup-based accounting of DMA-BUF allocations -- current review doc: https://firstname.lastname@example.org/
- Other dependencies for tracking shared gfx buffers now merged
- Improved community collaboration:
- Collaboration page set up: https://aosp-developers-community.github.io/
- Integrating v4l2_codec2 HAL on v4l2-compliant upstream codecs WIP
Qualcomm will provide an update on commercialization of a GKI-based target. This short talk will discuss the benefits to adopting GKI model (LTS intake frequency, upstream adoption) and some of the challenges we faced. Finally, we will discuss future challenges for GKI products with respect to upstream kernel development.
For various reasons, the Android Common Kernel (ACK) requires functionality that is not suitable for upstream. This talk will explore the reasons why this delta must exist, how it is maintained & managed and the steps taken to ensure that it remains as small as possible.
Starting with Android 13, Android Kernels can be built with Bazel. While under the hood this still uses KBuild as the authoritative build system, the guarantees a Bazel build provides are very valuable for building GKI kernels and modules. This talk will explore the Bazel based kernel build and the Driver Developer Kit (DDK) that provides a convenient way to create kernel modules in compliance...
ABI monitoring is an important part of the stability and upgrade-ability promises of the GKI project. In the latest generation of our tooling, we applied concepts from graph theory to the problem space and gained high confidence in the correctness and reliability of the analysis results. What else can we fit into this model and what would be most useful?
fw_devlink parses the firmware (device tree) to figure out device dependencies and uses that to enforce probe ordering and suspend/resume ordering between consumer and supplier devices. It is also used to implement sync_state() callbacks that let a supplier know when all its consumers have probed.
In this presentation, we'll talk about how some of the issues that were discussed in LPC 2021...
In this presentation we will talk about Protected KVM and the new virtualization APIs introduced with Android 13. You'll find out more about some of the key Protected KVM design decisions, its upstream status and how we plan to use protected virtualization for enabling a new set of use cases and better infrastructure for device vendors.
Cuttlefish is an Android based VM that can be used for kernel hacking amongst other things. We'll chat about how to set one up, put a mainline kernel on it, and utilize the devices it supports.
The file system in userspace, or fuse filesystem, is a long-standing filesystem in linux that allows a file system to be implemented in user space. Unsurprisingly, this comes with a performance overhead, mostly due to the large number of context switches from the kernel to the user space daemon implenting the file system.
bpf, or berkeley packet filters, is a mechanism to allow user space to...
EROFS is a readonly filesystem that supports compression. It is rapidly becoming popular in the ecosystem. This talk will explore its performance implications and space-saving benefits on the Android platform, as well as ideas for future work.
Multigenerational LRU (MGLRU) is a rework of the kernel’s page reclaim mechanism where pages are categorized into generations representative of their age. It provides a finer granularity aging than the current 2-tiered active and inactive LRU lists, with the aim to make better page reclaim decisions.
MGLRU has shown promising improvements from various platforms/parties. This presentation...
This presentation will talk about the usage of io_uring in Android OTA, present performance results. Android OTA uses dm-user which is a out of tree user space block device.
We plan to explore io_uring evaluating the RFC patchset : https://lore.kernel.org/io-uring/Yp1jRw6kiUf5jCrW@B-P7TQMD6M-0146.local/T/#m013adcbd97cc4c4d810f51961998ba569ecc2a62
Acting on the expectation that both device-tree and ACPI enabled systems must present a consistent view of the CPU topology, Sudeep submitted at  (currently v6) a series of patches that firstly fix some discrepancies in the CPU topology parsing from the DT /cpu-map node, as well as improve detection of last level cache sharing. ...
The Energy Model (EM) framework describes the CPU power model and is used for task scheduling decisions or thermal control. It's setup during the boot in one of the supported ways and is not modified during the normal run. Although, not every chip has the same power characteristics and cores inside might be sensitive to temperature changes in different way.
To address better the variety of...