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

Lennart Sorensen lsorense at csclub.uwaterloo.ca
Sun Jul 27 08:47:55 PDT 2014

On Sat, Jul 26, 2014 at 02:44:13AM +0000, Caoqiuhong wrote:
> The CPU model we use is big.LITTLE(4 at A7, 4 at A15), yes, it support using all 8 cores at once, and application could switch between A15 and A7 cluster.
> Now three SOC support 8 cores run at once, Exynos 5422, Kirin920 (these two are big.LITTLE cpu), MT6592 (8 cores A7).
> >>If it uses all 8 cores at once, is the cache coherency correctly enabled (The CCI)?
> Yes, CCI enabled, in order to ensure the cache coherency between each core in different clusters, only enable CCI could make 8 core run at once.
> I don't think the CCI cause the this issue. because MT6592 device is 8 core A7, no CCI feature, also have the same problem.

Yeah that does sound like it rules out caching issues.

> >>I have a system on my desk with 8 cores but the kernel doesn't support using the A7 cores yet (I should check if that has been fixed yet or not).
> You said BSP in you device doesn't support A7. Is that mean only run 4 at A15 core at once?
> Could you tell me what 8 cores device you use?  As I know, only few devices support 8 cores now.
> Such as Galaxy S5(Exynos 5422), Honor 6(Kirin 920), and some MT6592 devices.

I have an exynos5420 board (arndale-octa).  I know it is being worked
on, but last I checked it wasn't working yet for the A7 cores (trying
to boot the A7 cores caused an exception from the secure firmware).
I am building a new kernel to see if it has gotten better now.

I think the android builds for the board do support running in cluster
mode (so all A15 or all A7) but I couldn't care less about running

Len Sorensen

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