[Pixman] 答复: compatibility problem of Pixman on SOC system(such as ARMv7, or big.LITTLE)

Lennart Sorensen lsorense at csclub.uwaterloo.ca
Tue Jul 29 07:56:19 PDT 2014

On Sat, Jul 26, 2014 at 03:02:16AM +0000, Caoqiuhong wrote:
> Hi Lennart,
> I just want explain detail for you question, and some findings.
> >>Which CPU model are you using?  Does it support using all 8 cores at once, or does it switch between the A15 and A7 clusters?
> Not run A7 or A15 cluster separately, but run A7 and A15 cluster at once. truly 8cores, not 4 at A7, or 4 at A15 independently. 
> Some test I have done.
> 2 at A7 and 2 at A15 is ok at once, this issue just happen if the core count more than 4.
> In Android source code , I found pixman located in external/pixman, and static library cpufeatures will be linked in it's makefile.
> cpufeature is an android ndk module, it will open debug fs node in linux, such as follow,
> "/sys/devices/system/cpu/present"
> "/sys/devices/system/cpu/possible"
> if cpu present return value equal or less than 4, no such issue.
> if cpu present return value greater than 4, issue will happen.

Well my arndale-octa (Exynos 5420) still only runs 4 A15s and no A7s,
and apparently samsung doesn't give a shit about fixing it (apparently
the 5422 and 5800 work fine), and everyone else that does can't get access
to the right information because of samsung.  So I can't try it out.

Did you try the current version (0.32 I believe).  After all it could
be something that was already fixed.

Len Sorensen

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