[gentoo-amd64] Anybody else having problems with audio/vidio apps and glibc-2.5?

[Duncan]

I've been having all /sorts/ of problems with formerly stable audio and
video apps crashing recently.  The pattern is a crash at launch most (but
not all) of the time, often with some memory error.  However, if it
/does/ start and works more than a few minutes, it's fully stable and
will play for hours without issue.  xmms, kaffeine, amarok, all affected.

I didn't notice it until the upgrade to kde-3.5.5, which was my first big
set of apps built using the experimental CFLAG -ftree-vectorize as
discussed here a month or so ago, so I thought it was KDE. However, after
recompiling a bunch of stuff several different times/ways, nothing seemed
to be working.

Then I chanced across some ongoing discussion about nptl/linux-threads in
glibc-2.5 and forward on the dev list, while I was taking a break from
troubleshooting, and the thought occurred to me that glibc had been
upgraded at about the same time.

VWALLA!  I try to downgrade to glibc-2.4-r4, and get hit with its sanity
downgrade blocker.  It won't let me do it.  So a quick reboot to my backup
image (still on glibc-2.4-r3) and a quick ROOT=<backup> (which is main
working, since I'm no /on/ backup) export later, I'm emerging glibc-2.4-r4
(which I have binpkged, thanks to FEATURES=buildpkg) over top of what I'm
now convinced is a bad glibc-2.5.

Sure enough, reboot back to my main/working image again, now with
glibc-2.4-r4 once again, and **NO MORE CRASHES!!**

So... kde-3.5.5 with -ftree-vectorize is back in the clear.  The problem
is either glibc-2.5 itself, or -ftree-vectorize with it.  I haven't
figured out which yet, but I thought I'd post this both as a heads-up to
others and a question to see if anyone else has run into similar issues. 
I'll probably followup after I figure out which of those is the culprit or
if it's the combination.

Meanwhile a potentially useful trick to keep up your sleeve, just in case
you ever find yourself needing to downgrade glibc but the glibc ebuild
failing to let you do so.  Reboot to your emergency image, be that a
LiveCD or a backup set of partitions on your hard drive, mount your normal
working filesystem image, set ROOT= to point portage at the normal system
(not the backup), and /then/ do your glibc downgrade.  Then boot back to
your regular system and hope the downgrade works, as it did here. =8^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

-- 
gentoo-amd64@g.o mailing list