Removed assumption that any ARM build is ARMv7, fallback to ARMv6 to fix Raspberry Pi build

Removed assumption that any ARM build is ARMv7, fallback to ARMv6 to fix Raspberry Pi build


BUG=none
TEST=Build Chromium, test that build runs on Raspberry Pi (ie doesn't contain ARMv7 code)

[Liam McLoughlin, 2012-05-12 12:53:55]

As part of my series of changes to get a Chromium OS build running on the
Raspberry Pi. There appears to be an assumption in the ffmpeg code for Chromuim
that ARM==ARMv7. This patch corrects that assumption, to fallback to ARMv6 if
armv7==0.

[Ami GONE FROM CHROMIUM, 2012-05-12 15:10:13]

http://chromiumcodereview.appspot.com/10387100/diff/1/ffmpeg.gyp
File ffmpeg.gyp (right):

http://chromiumcodereview.appspot.com/10387100/diff/1/ffmpeg.gyp#newcode195
ffmpeg.gyp:195: ['target_arch == "arm" and armv7 == 0', {
Would this be better placed in src/build/common.gypi?  
(I'm not sure why the above ARM stanza is here, either)

[Liam McLoughlin, 2012-05-12 15:25:04]

On 2012/05/12 15:10:13, Ami Fischman wrote:
> http://chromiumcodereview.appspot.com/10387100/diff/1/ffmpeg.gyp
> File ffmpeg.gyp (right):
> 
> http://chromiumcodereview.appspot.com/10387100/diff/1/ffmpeg.gyp#newcode195
> ffmpeg.gyp:195: ['target_arch == "arm" and armv7 == 0', {
> Would this be better placed in src/build/common.gypi?  
> (I'm not sure why the above ARM stanza is here, either)

I just placed the non-ARMv7 condition here since this is where the ARMv7
condition was. Should it be in src/build/common.gypi?

[Ami GONE FROM CHROMIUM, 2012-05-12 15:28:09]

>
> I just placed the non-ARMv7 condition here since this is where the ARMv7
> condition was. Should it be in src/build/common.gypi?
>

Yes, I think so.
I need to make a change to the armv7 stanza above anyway in the next couple
of days so let me do that and see if any unrelated problems crop up, else
we can move your change to also live in common/build.gypi.
(the reason for potential complications is that while gyp controls how some
of the files are built, build_ffmpeg.sh controls how checked-in generated
source files are generated, including asm that hard-codes certain settings
like instruction set)
I'll ping this reviewlog when I know more.

[Ami GONE FROM CHROMIUM, 2012-05-14 18:22:53]

http://chromiumcodereview.appspot.com/10387100/diff/1/ffmpeg.gyp
File ffmpeg.gyp (right):

http://chromiumcodereview.appspot.com/10387100/diff/1/ffmpeg.gyp#newcode197
ffmpeg.gyp:197: '-mthumb',
Actually I'm surprised this CL works at all, considering build_ffmpeg.sh
hard-codes thumb, armv7, cortex-a8, etc to match l.177-190.
Are we getting lucky, or is there some reason this is working that I'm not
seeing?
(are you building against ffmpeg sources other than those generated by
build_ffmpeg.sh?)

[ilja, 2012-05-14 21:57:15]

I agree that it probably should be moved to common. In general there is a bit of
circularity here:
1) For convenience we use the CrOS toolchain to configure ffmpeg internally.
2) We manually set flags in gyp for the compiler settings.
3) AFAIK these compiler settings are mostly ignored by CrOS. But *probably* used
if you try to build with another compiler/toolchain. (In particular Android or
others.)

[Ami GONE FROM CHROMIUM, 2013-10-31 21:34:20]

Removing myself as reviewer to clean up my CL dashboard.