[mythtv] configure --enable-proc-opt

Janne Grunau janne-mythtv at grunau.be
Thu Sep 27 01:02:22 UTC 2007

On Thursday 27 September 2007 01:31:13 Daniel Kristjansson wrote:
> On Thu, 2007-09-27 at 01:05 +0200, Janne Grunau wrote:
> > Hi,
> >
> > --enable-proc-opt is currently not very useful. It trigeers in
> > trunk only the printing of two warning. It does not much more in
> > 0_20_fixes.
> >
> > I'm not sure if I should remove the option or if the automatic
> > setting of ARCHFLAGS should depend on it.
> Janne, after your ffmpeg merge a few weeks back you broke
> --disable-proc-opt, which was the default. I don't think
> this is a big deal as the optimized values are conservative
> anyway.

Argh, yes. It was cmov fix for via C3 cpus and I totally missed the 
effect of that code block.

> If someone needs a generic binary they can use the 
> --cpu, --tune, and --arch options, which is what all the
> distros use anyway. Also gcc has had support for these CPU
> types for a few years now, so very few people would need
> to add --cpu and --tune to ./configure in order to compile.

We could use the add_cflag function for the ARCHFLAGS which only adds 
its parameters if the compiler support it. ffmpeg's configure does it 
this way.
We should at least emit a warning if the compiler doesn't support that 
flag but compilation wouldn't fail.

> In 0.20-fixes, --disable-proc-opt it is still doing what was
> intended. We always compile for a Pentium Pro CPU on any x86_32
> processor, so that gcc can't be blamed for segfaults. With the
> exception of mmx which we check for. I think changing this in
> 0.20-fixes would be a mistake.

I had no intentions to change it in 0.20-fixes.


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