Re: problem : quantity of memory available

[Paul Brook <paul@codesourcery.com>]

On Thursday 28 October 2004 13:19, Fuhr Guillaume wrote:
> Hi !
>
> I run debian on a dual opteron system with kernel (
> kernel 2.6.7-5-amd64-k8-smp ) and 2GB of memory.
>
> I have add 4GB of memory on this computer and when i verify quantity of
> memory available (with "dmesg | grep Memory" for example), the result is  :
> Memory: 5081952k/6291456k available (1684k kernel code, 0k reserved, 987k
> data, 152k init)
>
> So i want to know why there is 1 GB that i can't use :(

This could be because of the PCI address space, although I thought this was 
only usually 0.5Gb.
This is usually located at the to of the 4G physical address space.
Some bios allow you to remap this section of physical memory above 4G so that 
all physical ram can be accessed. This is often disabled by default to 
provide the maximum amount of physical memory to legagy 32-bit operating 
systems.

Paul