Hi there!

I found a way to make X hang (ask me if interested), but after a
Alt+SysRq+k the system hangs completely.

Alt+SysRq+s-u-b works ok. If I try Alt+SysRq+k however,
a ~100x100 area on the screen blinks for a few seconds, the X image
disappears (i.e. the screen goes blank) and the system hangs completely.
Neither Alt+SysRq+s-u-b nor (Ctrl+)Alt-F? does work (no disk activity
at all) and I have to press the reset button.

I've been using 2.2.1+devfs with matroxfb on a Pentium 120 with
RedHat 5.1+ for a while now with no problems.
X is XF86_SVGA. Should I try XF86_FBDEV (not installed...)?


I have no good idea on how to try to locate this problem. It is 100%
repeatable however, so if someone gives me some ideas, I'm interested
in trying them...


Vital stats:

Kernel modules         2.1.121
Gnu C                  2.7.2.3
Binutils               2.9.1.0.4
Linux C Library        2.0.7
Dynamic linker         ldd (GNU libc) 2.0.7
Linux C++ Library      2.8.1
Linux C++ Library      2.8.1
Procps                 1.2.7
Mount                  2.8a
Net-tools              (1999-01-01)
Kbd                    0.94
Sh-utils               1.16


/Mikael


PS. I tried strace on the X-server during the crash. Here is the
result:

$ tail -n 470 /root/X.log  |head -n 30
gettimeofday({924875248, 997662}, NULL) = 0
select(128, [0 1 3 4 6 7 8 9 10 11 12 13 14 15 16 17 18], NULL, NULL,
{94, 620000}) = 1 (in [18], left {94, 620000})
read(18, "$\20\1\0+\0\1\0", 4096)       = 8
writev(18, [{"\1\2\344)\0\0\0\0\27\0\0\3\0\0\0"..., 32}], 1) = 32
gettimeofday({924875249, 1512}, NULL)   = 0
select(128, [0 1 3 4 6 18], NULL, NULL, {94, 616000}) = 1 (in [18],
left {94, 620000})
gettimeofday({924875249, 4489}, NULL)   = 0
select(128, [0 1 3 4 6 18], NULL, NULL, {94, 613000}) = 1 (in [18],
left {94, 620000})
read(18, "*\2\3\0\27\0\0\3\0\0\0\0\177\0\1"..., 4096) = 20
gettimeofday({924875249, 6217}, NULL)   = 0
gettimeofday({924875249, 6569}, NULL)   = 0
select(128, [0 1 3 4 6 7 8 9 10 11 12 13 14 15 16 17 18], NULL, NULL,
{94, 611000}) = 1 (in [18], left {94, 620000})
read(18, "\n\2\2\0:\0\0\3", 4096)       = 8
gettimeofday({924875249, 23956}, NULL)  = 0
writev(13, [{"\22\31[\6&\0\0\0:\0\0\3\0\0\0\3029652481
29652541
29652547
29652569
29652611
29652617
29652619
29652631
29652661
29652683
29652697
29652737
29652769
29652809
29652827
29652841

... continues a few hundred lines, then stops.

-- 
 ~~~ Mikael Nilsson ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   Student of Mathematics/Computer Science at Uppsala University.        
   Information wants to be free -- copyright protection is for dinosaurs! 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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