Hello eas-dev!
I'm pleased to announce that EAS development is moving to the next version of the android common kernel, android-4.9.
* EAS development will be done in a new android-4.9-eas-dev branch * android-4.9-eas-dev will be merged into android-4.9 twice during the period January - June 2018 * EAS functionality in android-4.4 is frozen * an android-4.4-eas-test branch is provided to help testing new EAS features on android-4.4 devices * assembly of an android common kernel based upon 4.14 is underway
Q&A:
* Why have you moved to android-4.9? * Partners developing devices have largely completed their android-4.4 derived device kernels and continuous development of EAS features is disruptive to tuning efforts * Device kernels derived from android-4.9 are in active development
* Will you deliver new EAS patches to android-4.4? * The plan is to only do fixes for critical bugs for android-4.4
* How will you be confident your patches are OK when you don't have devices running android-4.9 kernels yet? * This is the reason that the android-4.4-eas-test branch exists * This branch will contain patches which are merged into android-4.9-eas-dev and can be used to help test on device kernels derived from android-4.4 * The content will be whatever patches are necessary to be able to add patches from android-4.9-eas-dev cleanly, plus the patches from android-4.9-eas-dev * android-4.4-eas-test will be updated until we have a product quality device for testing with android-4.9 derived kernels
* What is the expected patch flow for testing eas-dev patches on android-4.4? * first cherry-pick the patches from android-4.4-eas-test to the device kernel * next cherry-pick in-development patches from android-4.9-eas-dev gerrit reviews * run tests to obtain power and performance numbers from real product-quality environments
* How critical are you going to be for patches sent to android-4.9-eas-dev? * Patches accepted there must be of good code quality and have at least one of the four necessary attributes: 1. Must reduce energy consumption 2. Must improve performance 3. Must bring android EAS closer to mainline 4. Must fix a bug * All patches must pass checkpatch.pl
* Given that you intend to merge android-4.9-eas-dev into android-4.9, will you freeze it at any time? * Yes. The intention is to have a 1 month stabilization ahead of each merge (January and June) * For the January merge, stabilization will begin December 1st, 2017. * For the June merge, stabilization will begin May 1st, 2018 * During stabilization, only fixes will be taken
* Will there be merges in-between January and June? * We do not plan to do this right now, but in principle it can be done
* When will android-4.4-eas-test update after android-4.9-eas-dev merges into android-4.9? * We intend to add patches to android-4.4-eas-test for review soon after merging them
* What happens if there is a bug in the merged branch? * A fix will be provided to android-4.9 and android-4.9-eas-dev * The fix will be reflected in android-4.4-eas-test
* Can I expect this to happen again any time soon? * Yes, there has been a new android common kernel based on a new LTS branch each year so far * Arm expects that pattern to continue * If the pattern holds, in October 2018 the target android kernel version for EAS development will be based on Linux 4.14 * We currently plan to use the same branching structure with the version numbers changed * Dates are projections based upon previous android releases and are subject to change * The kernel versions of eas-dev and eas-test branches are driven by the availability of suitable development and testing platforms, so are also subject to change
* What happens when you move to a 4.14 kernel? * After changes are reviewed and merged into android-4.9 from android-4.9-eas-test, those changes will be pushed for review on the 4.14 android branch * Anything merged in android's 4.14 branch which is broken will also be patched
Warmest Regards, Chris Redpath Open Source Software Power Team @ arm