Re: LDT_ENTRIES in ldt.h: why 8192?

From: Jakub Jelinek (jakub@redhat.com)
Date: Wed Feb 13 2002 - 15:27:56 EST


On Wed, Feb 13, 2002 at 12:18:48PM -0800, Seth D. Alford wrote:
> I'm getting "ldt allocation failures" on one of my systems. I know of Manfred
> Spraul's patch for this for 2.4.17. I'm using 2.4.12, though, and was
> wondering about an alternate solution. What would happen if LDT_ENTRIES was
> reduced, to, say, 4096, or 512, instead of 8192?
>
> .../include/asm-i386/ldt.h specifies:
>
> /* Maximum number of LDT entries supported. */
> #define LDT_ENTRIES 8192
>
> This was set to 8192 in version 0.99.15, in December, 1993, according to what I
> could find by retrieving different revisions of the kernel.

E.g. linuxthreads can eat up to 1024 LDT entries, but that's not very common.
IMHO there should be a single entry LDT, the emulation 5 entry LDT (current
default_ldt), 512 entries LDT (page) and then the full blown 8192 entries
LDT variants. Will post a patch once I finish it.

        Jakub
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