[FFmpeg-devel] Hacks on FATE

Reimar Döffinger Reimar.Doeffinger
Fri Sep 25 10:09:28 CEST 2009


On Thu, Sep 24, 2009 at 04:34:46PM -0700, Baptiste Coudurier wrote:
> On 09/24/2009 03:17 PM, M?ns Rullg?rd wrote:
> > Baptiste Coudurier<baptiste.coudurier at gmail.com>  writes:
> >> On 09/24/2009 12:42 PM, Michael Kostylev wrote:
> >>> [...]
> >>>
> >>> On i386 (HAVE_7REGS&&   HAVE_TEN_OPERANDS) may be equal to zero
> >>> (for example, on my machine %ebp is not available), then
> >>
> >> Speaking of ebp, configure check does not work with gcc 4.4 and
> >> therefore EBP is disabled. Considering gcc 4.4 will be the default
> >> compiler in ubuntu karmic, it may be nice to fix this in some way.
> >
> > What exactly is the problem?
> >
> 
> BEGIN /tmp/ffconf.2ssDOnLc.c
>      1   #include <signal.h>
>      2   static void sighandler(int sig){
>      3       raise(SIGTERM);
>      4   }
>      5   int main(void){
>      6       signal(SIGILL, sighandler);
>      7       signal(SIGFPE, sighandler);
>      8       signal(SIGSEGV, sighandler);
>      9   #ifdef SIGBUS
>     10       signal(SIGBUS, sighandler);
>     11   #endif
>     12       {     volatile int i=0;
>     13       __asm__ volatile (
>     14           "xorl %%ebp, %%ebp"
>     15       ::: "%ebp");
>     16       return i; }
>     17   }
> END /tmp/ffconf.2ssDOnLc.c
> gcc -D_ISOC99_SOURCE -D_POSIX_C_SOURCE=200112 -D_FILE_OFFSET_BITS=64 
> -D_LARGEFILE_SOURCE -std=c99 -fomit-frame-pointer -c -o 
> /tmp/ffconf.DBb5ytLJ.o /tmp/ffconf.2ssDOnLc.c
> /tmp/ffconf.2ssDOnLc.c: In function 'main':
> /tmp/ffconf.2ssDOnLc.c:17: error: bp cannot be used in asm here
> 
> Is this information sufficient ?

Well, it sure does not explain why you think this is an error in the
configure script, it seems to me gcc 4.4 makes it impossible to reliably
use ebp, i.e. it is a gcc bug/issue...



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