[yocto] [meta-raspberrypi][PATCH 2/2] x264: Fix build for armv6 RaspberryPi boards

[Andrei Gherzan]

On Mon, Apr 17, 2017 at 02:00:20AM +0000, Khem Raj wrote:
> On Sun, Apr 16, 2017 at 6:14 PM Andrei Gherzan <andrei at resin.io> wrote:
>
> > quant-a.S uses rbit thumb instruction unconditionally even though only
> > from ARMV6T2 this is available (which is not the case for RPI1, RPI0
> > etc). Avoid this by disabling asm.
>
>
> It would be bette to control it in component's own build system how much do
> we lose in performance if any do you know
>

I haven't tested myself but I know people who did and reported a 10%
performance hit.

Now I see two more options - other than this one:
1. Deactivate in configure ASM if not HAVE_ARMV6T2 - don't see any
fuctional difference
2. emulate rbit if not HAVE_ARMV6T2 - do you have any ideas on how to do
this? I'd like this solution as rbit is the only instruction failing so
we could take advantage of the other optimisations.

PS: in the meanwhile i merged it to unblock the builds.

--
Andrei Gherzan
gpg: rsa4096/D4D94F67AD0E9640 | t: @agherzan
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