new kernel on DS20

[Robson Francisco de Souza <rfsouza@citri.iq.usp.br>]

Hi,

I've just installed a fresh Debian 3.0 (woody) on a DS20 server (EV6,
EB264, Tsunami) and I was trying to compile a new kernel with SMP
support (2.4.18). I wasn't able to build a working 2.4 kernel from the
Debian stable kernel package, using gcc 2.95, so I tried to compile
2.2.20, which worked. I also tried to use version 2.2.25 from the
unstable area and both worked so I'm already able to use SMP, but the
kernel cannot see all memory on my system (4Gb RAM). Both 2.2.20 and 2.2.25
print a message like this

<boot>
Linux version 2.2.25 (herbert@escher) (gcc version 2.95.4 20011002
(Debian prerelease)) #1 SMP Wed Mar 19 11:21:52 CET 2003
Booting GENERIC on Tsunami variation Goldrush using machine vector DP264
from SRM
Command line: ro root=/dev/sdc2 mem=4096M
Cropping memory from 4096MB to 2048MB
SMP: 2 CPUs probed -- cpu_present_mask = 3
</boot>

"Cropping memory"???? Why does this happens? I found some references
about people not being able to use all memory on Alpha systems larger 
than 2Gb but all messages were older than 01/2000 and below kernel
version 2.2.15. I was also unable to find any configuration option for 
the kernel which could change such behaviour.

How can I force 2.2 kernels to see all the memory the server has?
Should I be using 2.4 kernels only?
If so, why do my compilations work but the 2.4 kernels do not work? They
end up in a "Kernel panic" message...

Thanks for any help,

Robson