[Android] Unaligned memory access on HTC OneX

[Ludovic Fauvet]

On Oct 5, 2012 10:02 AM, "XilasZ" <xilasz at gmail.com> wrote:
>
> As some of you may know, Tegra3 on the HTC OneX is a quad core, but there
is a big issue (at least on my device) :
>
> Core0 can do unaligned memory access, but the others can't, unaligned
access on core1/core2/core3 will trigger a SIGBUS signal which will crash
the app.
> libav use unaligned memory access when decoding on arm, i got random
SIGBUS crashes when playing h264 videos.
> We checked this with mru, it's not a bug in libav or vlc, so it's either
the cpu itself or the kernel (version 2.6.39.4 on my device).
>
> To workaround this, i use the attached patch, which disable unaligned
memory access. I never had a single SIGBUS crash since.
>
> I didn't notice any performance change, I guess it might be slower.
> I think we can do a little bench (edward ? :) ), and push it if it's
acceptable.
>
> What do you think ?

The OneX being a widespread device we can't just ignore the issue so do
what you have to do but a benchmark would be very welcome indeed.

-- 
Ludovic Fauvet
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