Re; 4KSTACKS again.

[Alan Cox]

On Sat, Apr 17, 2004 at 01:33:40PM -0700, Tom Mitchell wrote:
> I am curious why the change to 4K stacks was made.
> I assume from comments that it permits mapping an invalid page 
> to trap overflow errors.

You have a kernel stack per process. Thats a lot of memory. This stack is
used for syscall processing and also interrupts ocuring when that thread
runs. You may also get nested interrupts so the stack needs to be big
enough for a probable worst case, which means 4K or so alwayd free for
interrupts.

If you have 4K per process and seperate stacks per IRQ its more efficient
and more reliable.