Running an AMD k7-500 w/ an Asus motherboard and 2-128meg pc100 dimms. /proc/meminfo & top both only report 64 meg of memory. 256 Meg does show up in bios and when booting win98. I have not tried installing the 6.1 version yet.
Try adding append="mem=256MB" to the linux stanza of your /etc/lilo.conf.
The same happens with RH 6.1 and 2 x 256 MB DIMM on the same board (ASUS K7M): it only sees 64 of 512 MB. Adding "mem=512M" to the boot options in lilo.conf solved the problem.
My IBM Thinkpad 385D only see 64M; adding 'append="mem=80"' to /etc/lilo.conf fixes it. I thought the 2.2 kernel series was not supposed to have the 64M limit anymore?
It relies on a working BIOS to see over 64Mb. This causes the problems. 2.4 tries to use the same BIOS interface as Windows does on the basis the vendors might actually have tested it
I have a kernel crash at boot with the kernel option set to "mem=256M".
The kernel boot, and recognize 255M of memory with the kernel option "mem=255" instead of "mem=256".