Memmory Constraining at boot time
 

well, here´s the problem:

I have the following configuration

-Intel Itanium processor
-8GB ram (32x256MB)
-Debian Distro.
-Linux 2.6-test4 / Linux2.4 (have both)

For benchmarking issues I´m trying to limit the total ammount of memmory available for the system tests. To do so, I Use the 'mem=' option on the boot menu, just like:
"
Boot: <TAB>
Linux-2.6 Linux-2.4
>Linux-2.6 mem=1000m-5000m
"
to see the results just after the boot process finishes, I use "more /proc/meminfo"
So, for the following configurations of memmory I get the results:
- dont specify any mem configuration : total ammount <~8GB>
- limit to y, since y < = 1.3GB, : <~yGB>
- limit to 2GB : <~1.3GB>
- limit to 4 GB: <~1.3GB>
- any other way* of mem config. : <~1.3GB>

* meaning: mem=1000-3000 or mem=0-6000, any other....
I´ve already tried to divide the total ammount I want in pieces like: mem=0-256,500-1000, 2000-4000, .... but the result is always the same <~1.3GB> or less....

Thanks for any help.