During the changes leading up to the release of 6.5.1, certain openGl 
applications crash when changing to full screen mode (ie xmms openGL plugins). 
At the same time, rendering in compiz, became very slugginsh.

Mesa-20060810 is the last snapshot where these bugs did not occur.
These version up to this point have had extra glx debug info, namely the 
following.

Mesa: CPU vendor: AuthenticAMD
Mesa: CPU name: AMD Athlon(tm) XP 2600+
Mesa: MMX cpu detected.
Mesa: 3DNow! cpu detected.
Mesa: SSE cpu detected.
Mesa: Not testing OS support for SSE, leaving enabled.

Current 6.5.1 does not.

XMMS segfault strace tail 

poll([{fd=3, events=POLLIN}, {fd=8, events=POLLIN}, {fd=10, events=POLLIN}], 3, 
0) = 0
write(3, ">\0\7\0~\0\200\2\25\0\200\2,\0\200\2\317\0\0\0p\0\33\0"..., 76) = 76
read(3, 0xbfc1cb30, 32)                 = -1 EAGAIN (Resource temporarily 
unavailable)
poll([{fd=3, events=POLLIN, revents=POLLIN}], 1, -1) = 1
read(3, "\1\1R\16\0\0\0\0\27\0\200\2\0\0\0\0\0\0\0\0\35\0\0\0(\300"..., 32) = 
32
gettimeofday({1161996003, 701226}, NULL) = 0
ioctl(3, FIONREAD, [0])                 = 0
poll([{fd=3, events=POLLIN}, {fd=8, events=POLLIN}, {fd=10, events=POLLIN}], 3, 
6) = 0
gettimeofday({1161996003, 706948}, NULL) = 0
gettimeofday({1161996003, 706977}, NULL) = 0
ioctl(3, FIONREAD, [0])                 = 0
poll([{fd=3, events=POLLIN}, {fd=8, events=POLLIN}, {fd=10, events=POLLIN}], 3, 
0) = 0
gettimeofday({1161996003, 707083}, NULL) = 0
ioctl(3, FIONREAD, [0])                 = 0
poll([{fd=3, events=POLLIN}, {fd=8, events=POLLIN}, {fd=10, events=POLLIN}], 3, 
9) = 0
gettimeofday({1161996003, 717056}, NULL) = 0
gettimeofday({1161996003, 717231}, NULL) = 0
ioctl(3, FIONREAD, [0])                 = 0
poll([{fd=3, events=POLLIN}, {fd=8, events=POLLIN}, {fd=10, events=POLLIN}], 3, 
2) = 0
gettimeofday({1161996003, 719019}, NULL) = 0
gettimeofday({1161996003, 719162}, NULL) = 0
ioctl(3, FIONREAD, [0])                 = 0
poll([{fd=3, events=POLLIN}, {fd=8, events=POLLIN}, {fd=10, events=POLLIN}], 3, 
0) = 0
gettimeofday({1161996003, 719610}, NULL) = 0
ioctl(3, FIONREAD, [0])                 = 0
poll([{fd=3, events=POLLIN}, {fd=8, events=POLLIN}, {fd=10, events=POLLIN}], 3, 
7) = 0
gettimeofday({1161996003, 727235}, NULL) = 0
write(3, ">\0\7\0~\0\200\2\25\0\200\2,\0\200\2\320\0\0\0p\0\33\0"..., 76) = 76
read(3, 0xbfc1cb30, 32)                 = -1 EAGAIN (Resource temporarily 
unavailable)
poll([{fd=3, events=POLLIN, revents=POLLIN}], 1, -1) = 1
read(3, "\1\1V\16\0\0\0\0\27\0\200\2\0\0\0\0\0\0\0\0\35\0\0\0(\300"..., 32) = 
32
gettimeofday({1161996003, 731978}, NULL) = 0
ioctl(3, FIONREAD, [0])                 = 0
poll(
Segmentation fault

You've probably found a bug in XMMS, please visit
http://bugs.xmms.org and fill out a bug report.

[{fd=3, events=POLLIN, revents=POLLNVAL}, {fd=8, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 5) = 1
Process 19879 detached


(gdb) bt
#0  0xb56eeb30 in ?? ()
#1  0xb6c1b742 in __glXInitialize () 
from //usr//lib/opengl/xorg-x11/lib/libGL.so.1
#2  0x08182108 in ?? ()
#3  0x00000000 in ?? ()

Running on Athlon 2600XP w/ nforce2 board w/ AGP Radeon 8500LE