Building on the Treble and Generic System Image work, Android is
further pushing the boundaries of upgradibility and modularization with
a fairly ambitious goal: Generic Kernel Image (GKI). With GKI, Android
enablement by silicon vendors would become independent of the Linux
kernel running on a device. As such, kernels could easily be upgraded
without requiring any rework of the initial hardware porting efforts.
Accomplishing this requires several important changes and some of the
major topics of this year's Android MC at LPC will cover the work
involved. The Android MC will also cover other topics that had been the
subject of ongoing conversations in past MCs such as: memory, graphics,
storage and virtualization.
Proposed topics include:
Generic Kernel Image
ABI Testing Tools
Android usage of memory pressure signals in userspace low memory killer
Testing: general issues, frameworks, devices, power, performance, etc.
DRM/KMS for Android, adoption and upstreaming dmabuf heaps upstreaming
dmabuf cache managment optimizations
kernel graphics buffer (dmabuf based)
vitualization/virtio devices (camera/drm)
These talks build on the continuation of the work done last year as reported on the Android MC 2018 Progress report. Specifically:
Symbol namespaces have gone ahead
There is continued work on using memory pressure signals for uerspace low memory killing
Userfs checkpointing has gone ahead with an Android-specific solution
The work continues on common graphics infrastructure
If you are interested in participating in this microconference and have topics to propose, please use the CfP process. More topics will be added based on CfP for this microconference.
A year ago at Linux Plumbers, we talked about a generic Android kernel that boots
and runs reasonably well on any Android device. This talk shares the progress we've made so far on many fronts. A summary of those work streams, problems we discovered along the way and our plans for them. We will talk about our short term goals and long term vision to get Android device kernels as close to the...
The Kernel's API and ABI exposed to Kernel modules is not something
that is usually maintained in upstream. Deliberately. In fact, the
ability to break APIs and ABIs can greatly benefit the development.
Good reasons for that have been stated multiple times. See e.g.
The reality for distributions might look different though. Especially
- but not...
GKI or any ARM64 Linux distro needs a single ARM64 kernel that works across all SoCs. But having a single ARM64 kernel that works across all SoCs has a lot of hurdles. One of them, is getting all the SoC specific devices to be handed off cleanly from the bootloader to the kernel even when all their drivers are loaded as modules. Getting this to work correctly involves proper ordering of events...
An update on how we plan to enable multimedia testing on our 'cuttlefish' virtual platform. Overview of missing components for graphics virtualization.
The libcamera project was started at the end of 2018 to unify camera support on all Linux systems (regular Linux distributions, Chrome OS and Android). In 9 months it has produced an Android Camera HAL implementing the LIMITED profile for Chrome OS, and work is in progress to implement the FULL profile. Two platforms are currently supported (Intel IPU3 and Rockchip ISP), with work on...
Update and discussion of emulated storage on Android
This work proposes to adopt Extended FUSE (ExtFUSE) framework for improving the performance of Android SDCard FUSE daemon, thereby eliminating a need for out-of-tree WrapFS hackery in the Android kernel.
ExtFUSE leverages eBPF framework for developing extensible FUSE file systems. It allows FUSE daemon in Android to register “thin” eBPF handlers that can serve metadata as well as data I/O...
As part of the Android Microconference:
Linux Kernel Functional Test is a system to detect kernel regressions across the range of mainline, LTS and Android Common kernels. It is able to run a variety of operating systems from Linux to Android across an array of systems under test. You're probably thinking in terms of standard test suites like CTS, VTS, LTP, kselftest and so on and you're be...
A short update on eBPF in Android networking:
- how we're using ebpf in Android P on 4.9+ for statistics collection
and Q on 4.9+ for xlat464 offload, with a focus on the sorts of
problems we've run into
- where we'd like to go, ie. future plans with regard to xlat464/forwarding/nat
offload and XDP.
Topic will discuss how Android framework utilizes new kernel features
to better handle memory pressure. This includes app compaction, new
kill strategies and improved process tracking using pidfds.
To discuss recent developments and directions with DMABUF:
DMABUF Heaps/ION destaging
Better DMABUF ownership state machine documentation
DMABUF cache maintenance optimizations
Kernel graphics buffer idea
A short update on the status of DRM/KMS ecosystem adoption and how Google is improving verification of the DRM display drivers in Android devices.
Android has been using an out-of-tree schedtune cgroup controller for
task performance boosting of time-sensitive processes. Introduction of
utilization clamping (uclamp) feature in the Linux kernel opens up an opportunity to adopt an upstream mechanism for achieving this goal. The talk will present our plans on adopting uclamp in Android.