Messages in this thread | | | Subject | Re: [2.6 patch] i386: always use 4k stacks | From | Arjan van de Ven <> | Date | Sat, 17 Dec 2005 21:47:11 +0100 |
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On Sat, 2005-12-17 at 21:23 +0100, Paul Rolland wrote: > Hello, > > > One comment on x86-64 vs. x86: There are restrictions on where in > > memory your process stacks can be located on a 32-bit > > platform. They > > need to reside in lowmem, which means under certain circumstances > > your lowmem can get too fragmented to create new processes even > > though you still have a lot of available RAM. > > But where does these restrictions come from ? As far as I know, stack > is referenced to by SS:ESP registers, and nothing in the x86 architecture > prevents them from pointing outside of lowmem... Isn't this simply a > Linux design restriction ?
lowmem is a linux design restriction; only lowmem is directly addressable.
(also remember that you can have 36 bits of physical ram, but only 32 bit in a pointer, so even if lowmem wasn't 870Mb itd be limited to 4Gb)
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