lkml.org 
[lkml]   [2000]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: large memory support for x86
Date
> no, x86 virtual memory is 32 bits - segmentation only provides a way to
> segment this 4GB virtual memory, but cannot extend it. Under Linux there
> is 3GB virtual memory available to user-space processes.
>
> this 3GB virtual memory does not have to be mapped to the same physical
> pages all the time - and this is nothing new. mmap()/munmap()-ing memory
> dynamically is one way to 'extend' the amount of physical RAM controlled
> by a single process. I doubt this would be very economical though.
>
> Such big-RAM systems are almost always SMP systems, so eg. a 4-way system
> can have 4x 3GB processes == 12 GB RAM fully utilized. An 8-way system can
> utilize up to 24 GB RAM at once, without having to play mmap/munmap
> 'memory extender' tricks.

Why is it that a user process can't intentionally switch segments?
Dereferencing a 32-bit address causes the address to be calculated using the
"current" segment descriptor, right? It seems to me that a process could set
a new segment selector, in which case a dereference would operate on a whole
new segment. Is there a reason why processes are limited to a single
segment?

chris

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:41    [W:0.072 / U:28.440 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site