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and then of those interfaces, which ones need to actually be something other than a stub?
for example, wakelocks could probably be a stub, but an inter-process communications would have to actually work (I seem to remember reading that Android had a kernel assisted IPC protocol)
KS2011: Patch review
Posted Oct 25, 2011 8:08 UTC (Tue) by swetland (subscriber, #63414)
Some of the notable ones off the top of my head:
- binder (IPC subsystem) -- /dev/binder -- self-contained, in theory one could replace it with an entirely userspace implementation, in practice probably a lot of work
- logger driver -- /dev/logs/* -- multiple ring buffers for logging state without a lot of context switch overhead -- back when running on virtually tagged ARM9s this was very useful
- ION -- /dev/ion -- a unified approach to buffer management and sharing between display, GPU, camera, codecs, etc, new in Ice Cream Sandwich
Where possible we try to use standard interfaces -- for example, the power supply framework for battery charging and status, a lot of assorted interfaces via /sys, etc.
Posted Oct 25, 2011 8:17 UTC (Tue) by dlang (✭ supporter ✭, #313)
as for ION, since there is no code available yet, it's hard to talk about it.
Posted Oct 25, 2011 8:23 UTC (Tue) by swetland (subscriber, #63414)
We're still getting back online after the kernel.org downtime, so I don't have a handy URL for browseable source. Before kernel.org went down the ION kernel side sources were being developed in the open in the kernel repositories at android.git.kernel.org.
Hopefully it'll all be sorted out in the near future alongside the ICS userspace source release.
Posted Oct 25, 2011 18:01 UTC (Tue) by dlang (✭ supporter ✭, #313)
I am thinking that the interfaces needed to just make things 'run' on a kernel.org kernel is much smaller than what people have been trying to get submitted. And then once this smaller set is in place, things can be worked on much more easily.
while I have your attention, did you see Neil Brown's proposal for a userspace wakelock-type daemon? how hard would it be to modify the Android userspace to work with his proposal? As I understand it, there's only one daemon that actually talks to the kernel, everything else in the Android userspace talks to that daemon.
Posted Oct 25, 2011 9:31 UTC (Tue) by xav (subscriber, #18536)
Posted Oct 26, 2011 15:37 UTC (Wed) by email@example.com (subscriber, #74477)
dmabuf just deals with buffer sharing.
I imagine CMA + dmabuf would displace ION.
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