[MPlayer-DOCS] Fwd: Re: [MPlayer-dev-eng] wmv9dmod.dll load failure: bug report + patch

[Diego Biurrun]

Hi!

Could you come up with a small that adds this to the FAQ?  That would
be much appreciated, since I am not sure I can make complete sense of
what is written below.
Thanks

Diego

P.S.: Or maybe somebody else from the docs team wants to do it ;)

Arpi writes:
 > 
 > could u pls add this to the docs/faq?
 > 
 > --------- Forwarded message ---------
 > From: Alex Eskin <alexeskin at yahoo.com>
 > To: mplayer-dev-eng at mplayerhq.hu
 > Subject: Re: [MPlayer-dev-eng] wmv9dmod.dll load failure: bug report + patch
 > 
 > 
 > Ok this is a fedora problem which also affects
 > wine. There is no workaround which is local to
 > mplayer alone, but the following works:
 > 
 > 1) edit /etc/syconfig/prelink and change
 > change PRELINK_OPTS=-mR
 > 
 > to PRELINK_OPTS="-mR --no-exec-shield"
 > 
 > 2) touch /var/lib/misc/prelink.force
 > 3) /etc/cron.daily/prelink 
 > (this relinks all the applications, and it takes
 > quite a while). 
 > 
 > What is happening is the following (taken from the
 > wine mailing list):
 > 
 > The loading addresses for system libraries are changed
 > once per week (or 2 weeks, don't remember). System
 > libraries added after the last complete assignation
 > are assigned a random address at each load, so is you
 > try to execute 10 times in a row the same program,
 > it'll fail some of the time and succeed the remaining
 > times.
 > 
 > Disabling exec-shield (either via setarch i386 or with
 > the proc thing) works sometimes, depending on the
 > loading addresses assigned to libraries. If something
 > (libc, libm, libdl, etc.) uses that address, nothing
 > Win32 will be usable. When exec-shield is disabled,
 > new libraries will be assigned loading addresses
 > starting at the lower value possible, but already
 > assigned ones (via prelinking) will still keep theirs,
 > hence possibly blocking execution. 
 > 
 > 
 > Would you  accept a patch which detects this condition
 > and sends the user somewhere for a workaround?
 > 
 > --- Vladimir Mosgalin <mosgalin at VM10124.spb.edu>
 > wrote:
 > > On Wed, 4 Feb 2004, Alex Eskin wrote:
 > > 
 > > AE>Could the problem have something to do with
 > > prelink?
 > > 
 > > It is possible. First, try turning off prelink -
 > > there was some way to
 > > do this for single application. Second, with some
 > > security patches
 > > allowing execution in stack area may be needed,
 > > since kernel disallows
 > > it unless it is explictly requested, and this is
 > > needed for some windows
 > > dlls in mplayer.
 > > 
 > > To do this, get a program called 'chstk'. It's in
 > > kernel-utils package
 > > in my distribution (asp9), but I guess it should
 > > present in fedora, or
 > > use rpmfind to locate it. Then, run /usr/sbin/chstk
 > > -e /usr/bin/mplayer
 > > and tell if the problem will go away.