Re: sdram and linux
On Mon, 30 Mar 1998, Stephen Carpenter wrote:
> anyway memtest86 boots on its own anyway... quick Q: does memtest86
> work on SDRAM ? I know it doesn't work on ECC or Parity ram? I will
> dfind out tonight...I am trowing 64 MB od SDRAM in my machine (nice
> upgrade from 32 MB of old SIMMs)
Well, I've had a few problems when I installed some new sdram on my
computer, too. memtest86 didnt saw them, but i had a few wierd problems,
programs segfaulting and all.
Apparently part of the reason was that some memory access patterns can't
be reproduced with just the CPU : you may also have some other chips
accessing memory, and the problems may happen only when the different
accesses happen in some particular order. Thus, your memory will only fail
if you have, say, a disk access and a network access at the same time as a
compile.
The way I tested my bad sdram was to use this script :
tar czf linux.tar.gz linux
mv linux linux.orig
for i in 0 1 2 3 4 5 6 7 8 9
do
for j in 0 1 2 3 4 5 6 7 8 9
do
for k in 0 1 2 3 4 5 6 7 8 9
do
echo $i$j$k
tar xzf linux.tar.gz
diff -U 2 -rN linux.orig linux
rm -fr linux
done
done
done
mv linux.orig linux
I had one of them running on each of my disks (1 IDE with triton
busmatering, 1 SCSI). Then I compiled kernels in the background. I had
both some sig11 problems, and some differences output by the "diff" in the
script (btw, there was a strange pattern in these differences).
problem went away when I exchanged my sdram at the store. They said it
wasnt the reason, and that their sdram was okay, but I know this wasnt
true. I guess they must have sold my faulty sdram to some win95 user who
wont see the difference anyway - he'll just get a few more crashes than
average...
Michel "Walken" LESPINASSE - Student at Ecole Centrale Paris (France)
www email : walken@via.ecp.fr
(o o) www : http://www.via.ecp.fr/~walken/
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