Hi...

On Wed, Apr 7, 2010 at 06:27, Youngwhan Song <breadn...@gmail.com> wrote:
> What if actual physical memory is only 256MB? How does kernel divide virtual
> memory?

Still the same as before, 3:1 vm split, 896 MB in ZONE_NORMAL and so
on. However, in this case there is no ZONE_HIGHMEM since all memory
cells are directly addressable

>Do we need to specify the region to kernel? Or will kernel itself
> decide it automatically?

Practically (this is something that I just rather guess, but I am
pretty confident), the kernel will be mapped to somewhere around the
first 10-100 MiB, leaving the reserved BIOS memory hole. Thus, the
rest are available for dynamic allocation, be it for user space or
kernel space. Virtually, thanks to the page table mapping, it will
look like single continous address space where user space takes the
first 3 GiB and kernel uses the upper 1 GiB.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

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