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Date: Wed, 13 Feb 2002 15:27:56 -0500
From: Jakub Jelinek <jakub@redhat.com>
To: linux-kernel@vger.kernel.org
Subject: Re: LDT_ENTRIES in ldt.h: why 8192?
Message-ID: <20020213152756.F21624@devserv.devel.redhat.com>
Reply-To: Jakub Jelinek <jakub@redhat.com>
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In-Reply-To: <20020213121848.A31469@mallard.plaza.ds.adp.com>; from setha@plaza.ds.adp.com on Wed, Feb 13, 2002 at 12:18:48PM -0800
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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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