RAM upgrade ignored or kernel panic arises on Thinkpad T22

[Virgil <virgilinux@yahoo.com>]

Running Debian Woody Kernel 2.4.18 on an IBM Thinkpad T-22.
Upgraded RAM from 128M to 256M.
Windows XP recognizes new RAM, and apparently has no difficulties with
it.

Linux does NOT seem to recognize the added RAM.

free
             total       used       free     shared    buffers    
cached
Mem:        125876     121812       4064          0       4040     
51304
-/+ buffers/cache:      66468      59408 

grep '^Memory' /var/log/dmesg
Memory: 125596k/131072k available (1783k kernel code, 5008k reserved,
549k data, 280k init, 0k highmem)

Following instructions given in:
http://www.webmo.net/support/linux_memory.html

I added 
append="mem=256M"
to lilo.conf and ran and executed /sbin/lilo -v

A warm re-boot has no effect, but a cold reboot ends in kernel panic
"unable to handle kernell null pointer dereference at virtual address
00000003.

Could it be that I may have accidentally limit my kernel to 128M during
installation?

Deleting (via rescue disk) the added line eliminates the kernel panic,
but of course only 128M of memory are used. Bottom line, I cannot use
the upgraded memory with Linux.

Much "googling" has not produced a solution.

Thanks for your help.

__Virgil

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