Android Mainlining Project
This page is for organizing the Android Mainlining Project. It has information and resources associated with this project.
Contents
Goal
The goal of this project is to ultimately mainline all patches required to run the current released version of Android. The purpose of mainlining these patches is 3-fold:
- to allow a developer to use the latest released version of the Linux kernel to run an Android system, without requiring patches to their kernel
- to make it possible to develop drivers and board support features against either an Android kernel release or a kernel.org kernel release, with little or no modifications or conditional code
- to reduce or eliminate the burden of maintaining independent patches from release to release for Android kernel developers
To "mainline" a patch means to have it included in Linus Torvalds kernel.org kernel, in a released (non-rc) version.
Process
[This is a draft section, up for discussion]
Overall:
- identify all patches/features, and categorize into core or non/core
- core = feature is required or strongly desired for Android operation on a platform
- non-core = Most of the Android system can run without the feature
Per feature or patch:
- research any previous submission feedback
- incorporate feedback, as appropriate
- negotiate any interface changes with Google Android team
- submit updated patches to mainline
- repeat until accepted
Resources
- Mailing list for discussions is at: https://lists.linuxfoundation.org/mailman/listinfo/ce-android-mainline
- Linaro blueprint for project: https://blueprints.launchpad.net/linux-linaro/+spec/linaro-kernel-android-upstreaming
People
People who have expressed interest in this:
- Tim Bird
- John Stultz
- Paul McKenney
- Deepak Saxena
- Arnd Bergmann
- Thomas Gleixner
- Arjan Van de Ven
- Brian Swetland
- Tetsuyuki Kobayashi
- Andy Green
- Victor M. Jaquez
- Jesse Barker
- Anton Vorontsov
- Greg Kroah-Hartman
roles/expertise
This section has miscellaneous notes on roles, capabilities and expertise of group's members
John Stultz is the owner of the Linaro blueprint for mainlining Android features. Tim Bird is the owner of the CE Workgroup project for mainlining Android features. Deepak and Jesse can help make arrangements for a meeting at Linaro Connect. Tim can help make arrangements for a meeting at Android Builders Summit.
- John Stultz has worked on POSIX Alarm timers
- Jesse is working on shared memory buffers related to pmem/CMA/parts of ion
- Anton Vorontsov is looking at the lowmemory killer
- Greg has put some Android patches into mainline (under drivers/staging/android) previously
- Greg put some Android patches in mainline under drivers/staging/android in Dec. 2011
- Paul McKenney - kicking around ideas for dealing with wakelocks single global lock (dec. 2011)
Plans
- Set up mailing list - Tim is working on it - probable name: ce-android-mainline@list.linuxfoundation.org
- Set up meeting at Linaro Connect or ABS - Tim (with Deepak and/or Jesse's help)
- Update this page with latest info (for December 2011) - Tim
- Make a general announcement of the project to celinux-dev and linux-embedded - Tim
Patch/Feature Status Chart
Feature/Patch | Description | Status | Part of core? | Owner/Interested parties | Notes |
---|---|---|---|---|---|
logger | kernel support for Android system logging | not mainlined (but see linux-next staging as of 12/19/11) | yes | Tim Bird | should be non-controversial (though I'm always surprised)
See Mainline Android logger project for a list of ideas, issues and a project plan for this feature |
wakelocks | Power management locking mechanism to prevent opportunistic suspend | not mainlined | yes | Rafael Wysocki | Is important due to impact on board support and drivers by 3rd parties |
Android alarm timers | Timers that count down during suspended operation, and can wake from suspend | Partial: Posix alarm timers were mainlined in kernel version 2.6.38 - see https://lwn.net/Articles/429925/ | yes | John Stultz | Mending patches to convert Android Alarm Timers to utilize the upstreamed alarm timer work are still pending. |
ashmem | Shared memory implementation that allows unpinned pages to be marked, which can be dropped by the kernel under memory pressure | not mainlined | yes | John Stultz | Working on fadvise volatile alternative implementation that handles part of the ashmem functionality. However, there are additional aspects of ashmem design that need to be addressed(no tmpfs mounts, atomic create/unlink behavior,etc). |
network security | special permission checks for secure access to network operations | not mainlined | ? (can run without it, but network security won't be enforced) | no one | May be very difficult to mainline, as the code is extremely Android-specific with hardcoded GIDs and capabilities. |
binder | Android inter-process communication mechanism | not mainlined (but see linux-next staging as of 12/19/11) | yes | no one | Generated a fair amount of discussion on last submission. See http://elinux.org/Android_Binder#obstacles_to_mainlining |
pmem | |||||
Android USB gadget driver | |||||
wireless features | (more specific please?) | ||||
timed gpio | perform gpio operations as a result of specified timeouts | not mainlined (but see linux-next staging as of 12/16/11) | |||
low memory killer | feature to manage application lifecycle in low memory conditions | not mainlined (but see linux-next staging as of 12/16/11) | yes (but system might work without it) | Anton Vorontsov | See https://lkml.org/lkml/2011/12/18/173 for discussion about these patches |
ram console | ability to save console output to a reserved ram area for diagnostics on a subsequent boot | not mainlined (but see linux-next staging as of 12/16/11) | no | no one | |
timed output | |||||
ion graphics memory driver | graphics memory drivers thingie | not mainlined | yes (for 4.0 and later?) | Jesse Barker |
Progress Chart
This section is intended to show our progress, by showing the patch set size over time. With any luck, as we get features into mainline, the difference between the Android kernel and the legacy Linux kernel will shrink.
- diff of 2.6.29 kernel.org tree versus kernel
Kernel Version | Files changed | insertions | deletions | hunks | bytes in diff |
---|---|---|---|---|---|
2.6.29 | 187 | 123506 | 0 | 187 | 3291827 |