[FFmpeg-devel] [RFC] insufficient VFP check?

Måns Rullgård mans
Sun Jan 17 12:53:15 CET 2010

Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:

> On Sun, Jan 17, 2010 at 12:31:02AM +0000, M?ns Rullg?rd wrote:
>> M?ns Rullg?rd <mans at mansr.com> writes:
>> > Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
>> >> Uh, can the -unknown- variant compile vfp/neon?
>> >> I came to the conclusion, idiotic as it is (not commenting on the technical
>> >> point, but from a usability one), that softfloat is necessary
>> >> to have neon/vfp support.
>> >
>> > Hmm, I didn't read carefully enough first time, and missed the
>> > softfloat part.  You definitely do *not* want to mess with softfloat
>> > on A8.  The softfloat compilers are configured to emulate FP, and the
>> > -mfloat-abi=softfp flag contradicts that.  No idea what that might
>> > lead to.
>> >
>> > With a softfloat compiler I get the same error.
>> Mystery solved: running gcc with -v reveals the assembler invocation
>> to be this:
>> /usr/libexec/gcc/arm-softfloat-linux-gnueabi/as --gdwarf2 -mcpu=cortex-a8 -mfpu=softvfp -meabi=4 -o libavcodec/arm/dsputil_vfp.o /tmp/ccsHJvmR.s
>> The -mfpu=softvfp there means all manner of FP is out of the question.
>> Oddly enough, non-softfloat compilers will happily compile to
>> softfloat if only given the -msoft-float flag.
> Well, in my previous try with non-softfloat toolchain it couldn't
> compile since it could not find -lfloat (which it wanted to use even
> with -mfloat-abi=softfp -mfpu=neon).

Never seen anything like that.  Where do you get your compilers?
Perhaps you should consider another vendor.

M?ns Rullg?rd
mans at mansr.com

More information about the ffmpeg-devel mailing list