On Mon, Jan 11, 2016 at 3:07 PM, Richard Purdie <[email protected]> wrote: > On Mon, 2016-01-11 at 14:58 -0800, Khem Raj wrote: >> > On Jan 7, 2016, at 3:40 PM, Phil Blundell <[email protected]> wrote: >> > >> > On Thu, 2016-01-07 at 14:29 -0800, Andre McCurdy wrote: >> > > FULL_OPTIMIZATION_armv7a = "-fexpensive-optimizations -fomit >> > > -frame-pointer -O4 -ffast-math" >> > > +FULL_OPTIMIZATION_armv7ve = "-fexpensive-optimizations -fomit >> > > -frame-pointer -O4 -ffast-math" >> >> O4 ? may be just replace this whole thing with -Ofast now a days >> -fexpensive-optimizations is enabled at -O2,-O3 anyway same for fomit >> -frame-pointer and -Ofast turns on >> feast-match on top of -O3 >> >> > I wonder if this would be better as just FULL_OPTIMIZATION_arm. >> > That >> > said, the OPTIMIZATION variables are primarily distro knobs and >> > it's not >> > entirely clear that individual packages ought to be overriding them >> > at >> > all. >> > >> > Does anybody know whether there is any actual science behind the >> > use of >> > those flags on armv7a specifically? >> >> it came into ffmpeg circa 2008 and proliferated into related >> components primarily to support vectorization and neon >> which was quite nascent for ARM architecture in those days in gcc. >> Today if you were to configure libav with default options >> then it uses mainly -fomit-frame-pointer-O3 -fno-math-errno -fno >> -signed-zeros -fno-tree-vectorize >> >> which is primarily -Ofast -fno-tree-vectorize > > I have to admit that my personal instinct on these is simply to remove > them. I doubt they're buying much now and if people really want to tune > specific recipes by hand they still can do so from their local/distro > config.
It's the other armv7a over-ride which probably needs more careful consideration, ie: EXTRA_FFCONF_armv7a = "--cpu=cortex-a8" Khem, did you look into that? What happens to libav if we don't configure for a suitable CPU? > Cheers, > > Richard > > -- > _______________________________________________ > Openembedded-core mailing list > [email protected] > http://lists.openembedded.org/mailman/listinfo/openembedded-core -- _______________________________________________ Openembedded-core mailing list [email protected] http://lists.openembedded.org/mailman/listinfo/openembedded-core
