[MPlayer-dev-eng] [PATCH] configure & MEMALIGN_HACK

Björn Sandell biorn at dce.chalmers.se
Tue Jan 4 23:28:05 CET 2005

On Tue, 4 Jan 2005 23:04:34 +0100
Sascha Sommer <saschasommer at freenet.de> wrote:

> On Tuesday 04 January 2005 21:10, Björn Sandell wrote:
> >
> > mplayer in free(): error: modified (chunk-) pointer
> >
> > MPlayer interrupted by signal 6 in module: uninit_vcodec
> > - MPlayer crashed. This shouldn't happen.
> >   It can be a bug in the MPlayer code _or_ in your drivers _or_ in
> >   your gcc version. If you think it's MPlayer's fault, please read
> >   DOCS/HTML/en/bugreports.html and follow the instructions there. We
> >   can't
> > and won't help unless you provide this information when reporting a
> > possible bug.
> >
> > hence I suggest a patch like the attached.
> Can you find out why this happens or send a backtrace?

It's av_free() in libavcodec/mem.c that calls free() with a bad pointer.
I'll try to get a better description/backtrace.

> Do the BSDs really have no memalign?

No. malloc() returns a pointer that is "suitably aligned (after possible
pointer coercion) for storage of any type of object".

> I'm afraid this fix is needed on BSD, too otherwise SSE instructions
> will just lead to a segfault on P4 if the buffers aren't aligned
> correctly.

Well, then we would have seen those segfaults a month ago, but I didn't.
(acutally I have a PIII, but I'm sure someone would have told me :)

Björn Sandell           Chalmers University of Technology
IT department    www.ita.chalmers.se   +46 (0)31 772 1000

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