Thinkpad 560X w/ 160MB memory (2.4.24 kernel): many segfaults

[Sanjoy Mahajan]

I 'upgraded' my IBM Thinkpad 560X laptop to 160MB of RAM: 32MB on the
motherboard plus a 128MB EDO SODIMM.  Even though IBM says that the
motherboard is certified only up to 96MB, it recognized the memory
fine on boot.  Linux booted and noticed the 160MB without needing any
kernel command line options.

On the thinkpad mailing list (where I got the idea to upgrade) people
mentioned that Win2K on a 560X can deal with the extra memory, but for
Win9x one needs to change the video driver memory ranges (adding
0xF0000000 to the standard values).  So I worried that X windows might
have a similar problem.

But everything worked fine at first, even X (I'm using XFree86 4.1.0).

However, I soon found that many programs would segfault for no obvious
reason.  For example, the galeon browser and emacs (in X windows) died
on their own, whereas they almost never did before.  That seemed
consistent with the worry about X.

To check that it wasn't the memory module itself, I ran the BIOS
memory test (which passed) and also memtest86+ (no errors on 4 passes,
which was more than 2 hours of testing).

For other reasons I was recompiling the kernel (2.4.24).  Various
steps, all unrelated to X, failed as well: e.g. 'make menuconfig'.  To
be sure that it wasn't due to X windows interacting badly with
something else, I switched to single user and reran the compile.  Here
are the last few lines of a resulting logfile for 'make menuconfig':

  make -C scripts/lxdialog all
  make[1]: Entering directory `/usr/src/linux-2.4.24/scripts/lxdialog'
  gcc -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -DLOCALE
  -DCURSES_LOC="<ncurses.h>" -c -o checklist.o checklist.c
  gcc -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -DLOCALE
  -DCURSES_LOC="<ncurses.h>" -c -o menubox.o menubox.c
  gcc: Internal compiler error: program cc1 got fatal signal 11
  make[1]: *** [menubox.o] Error 1
  make[1]: Leaving directory `/usr/src/linux-2.4.24/scripts/lxdialog'
  make: *** [menuconfig] Error 2

I have the core file if it would be useful.  It doesn't help much
because cc1 is compiled with optimization.  Here is what gdb says upon
starting up with that core file:

  Core was generated by `/usr/lib/gcc-lib/i386-linux/2.95.4/cc1
  /tmp/ccoqJbGF.i -quiet -dumpbase menubox'.
  Program terminated with signal 11, Segmentation fault.

Once, make-kpkg (a Perl script) segfaulted; another time, 'sh'
segfaulted.

As a final control, I took out the 128MB module and replaced it with
the original 64MB module.  The whole kernel compile worked fine and
the machine is working perfectly, as it did before the upgrade.

Could this issue be due to the kernel?  Perhaps the VM system is not
adjusting everything it needs to for the new memory?  Any tests I can
run to narrow it down?

Perhaps useful specs on the machine:

Model: 2640-70U
CPU: Pentium-MMX 233MHz
L1 : 16KB
L2 : 256KB (although memtest86+ said unknown)
Chipset: 430TX (I think)
Kernel: 2.4.24

-Sanjoy
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