Re: Possible Pentium MMX CPU bug?

Yuri Kuzmenko (yuri@microsoft.kiev.ua)
Fri, 28 Nov 1997 18:16:37 +0200

In article <19971128153752.49422@thelonious.new.ox.ac.uk> you wrote:
AS> Ingo Molnar (mingo@pc7537.hil.siemens.at) wrote:
>> I think i have found the reason why certain applications (Quake, GCC)
>> crash on certain Pentium MMX processors. I suspect it is a CPU bug. I have
>> a testprogram that detects this bug/condition, and have made a Linux
>> kernel patch that is a first attempt to work the bug around.

yuri@cs:~$ ./a.out
testing bug ... possible Pentium MMX 'missed write' CPU bug detected!

yuri@cs:~$ cat /proc/cpuinfo
processor : 0
cpu : 586
model : 4
vendor_id : GenuineIntel
stepping : 3
fdiv_bug : no
hlt_bug : no
f00f_bug : yes
fpu : yes
fpu_exception : yes
cpuid : yes
wp : yes
flags : fpu vme de pse tsc msr mce cx8 mmx
bogomips : 522.65

It's Pentium 166 MMX (overclocked to 266 mhz).

quake2test make core dump now. In next hour I try to run quake2test with
pathced kernel.

AS> miles:adam~$ ./mwbug
AS> testing bug ... no Pentium MMX 'missed write' bug in this CPU.
AS> miles:adam~$ cat /proc/cpuinfo
AS> processor : 0
AS> cpu : 586
AS> model : Pentium MMX
AS> vendor_id : GenuineIntel
AS> stepping : 3
AS> fdiv_bug : no
AS> hlt_bug : no
AS> sep_bug : no
AS> f00f_bug : yes
AS> fpu : yes
AS> fpu_exception : yes
AS> cpuid : yes
AS> wp : yes
AS> flags : fpu vme de pse tsc msr mce cx8 mmx
AS> bogomips : 400.59

AS> It's a 200MHz CPU.

AS> Let me know if I can be of further assistance.