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From: Rusty Russell <rusty@rustcorp.com.au>
To: Ingo Molnar <mingo@elte.hu>
Cc: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Zachary Amsden <zach@vmware.com>,
	Jeremy Fitzhardinge <jeremy@xensource.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andi Kleen <ak@suse.de>,
	pazke@donpac.ru
Subject: Re: [PATCH 1/8] Remove cpu_gdt_table: use boot_gdt_table until migration to per-cpu
Date: Wed, 07 Mar 2007 11:22:15 +1100	[thread overview]
Message-ID: <1173226935.4644.66.camel@localhost.localdomain> (raw)
In-Reply-To: <20070306132004.GD9031@elte.hu>

On Tue, 2007-03-06 at 14:20 +0100, Ingo Molnar wrote:
> * Rusty Russell <rusty@rustcorp.com.au> wrote:
> 
> > +/* The boot Global Descriptor Table: after boot we allocate a per-cpu copy */
> >  	.align L1_CACHE_BYTES
> >  ENTRY(boot_gdt_table)
> > -	.fill GDT_ENTRY_BOOT_CS,8,0
> > -	.quad 0x00cf9a000000ffff	/* kernel 4GB code at 0x00000000 */
> > -	.quad 0x00cf92000000ffff	/* kernel 4GB data at 0x00000000 */
> > -
> > -/*
> > - * The Global Descriptor Table contains 28 quadwords, per-CPU.
> > - */
> > -	.align L1_CACHE_BYTES
> > -ENTRY(cpu_gdt_table)
> >  	.quad 0x0000000000000000	/* NULL descriptor */
> >  	.quad 0x0000000000000000	/* 0x0b reserved */
> > -	.quad 0x0000000000000000	/* 0x13 reserved */
> > -	.quad 0x0000000000000000	/* 0x1b reserved */
> > +	.quad 0x00cf9a000000ffff	/* boot: 4GB code at 0x00000000 */
> > +	.quad 0x00cf92000000ffff	/* boot: 4GB data at 0x00000000 */
> >  	.quad 0x0000000000000000	/* 0x20 unused */
> >  	.quad 0x0000000000000000	/* 0x28 unused */
> >  	.quad 0x0000000000000000	/* 0x33 TLS entry 1 */
> 
> actually, the reason for the small boot GDT was that some systems 
> wouldnt even boot with a larger GDT. (there was some BIOS interaction, 
> forgot what it was - iirc it was mach-visws and also some other older 
> box)

Thanks for the explanation: I did wonder!  I left the descriptor
truncated to just the first few entries, so I'm *pretty sure* it won't
matter: the layout is identical.

I'd really like to try it and see, though; Andre?
Rusty.



  parent reply	other threads:[~2007-03-07  0:22 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-06 12:39 [PATCH 0/8] x86 boot, pda and gdt cleanups Rusty Russell
2007-03-06 12:53 ` [PATCH 1/8] Remove cpu_gdt_table: use boot_gdt_table until migration to per-cpu Rusty Russell
2007-03-06 12:54   ` [PATCH 2/8] Remove NR_CPUS from asm-generic/percpu.h Rusty Russell
2007-03-06 12:55     ` [PATCH 3/8] Use per-cpu variables for GDT, PDA Rusty Russell
2007-03-06 12:57       ` [PATCH 4/8] Cleanup setup_pda Rusty Russell
2007-03-06 12:58         ` [PATCH 5/8] Cleanup GDT access Rusty Russell
2007-03-06 13:00           ` [PATCH 6/8] Allow per-cpu variables to be page-aligned Rusty Russell
2007-03-06 13:01             ` [PATCH 7/8] Page-align the GDT Rusty Russell
2007-03-06 13:03               ` [PATCH 8/8] Convert PDA into the percpu section Rusty Russell
2007-03-06 13:10                 ` Ingo Molnar
2007-03-07  0:12                   ` Rusty Russell
2007-03-07  0:35                     ` Jeremy Fitzhardinge
2007-03-06 18:28                 ` Jeremy Fitzhardinge
2007-03-06 19:34                 ` Andi Kleen
2007-03-06 18:37                   ` Jeremy Fitzhardinge
2007-03-07  0:33                   ` Rusty Russell
2007-03-07 11:55                     ` Rusty Russell
2007-03-13 17:15                 ` Jeremy Fitzhardinge
2007-03-14  2:27                   ` Rusty Russell
2007-03-06 13:15             ` [PATCH 6/8] Allow per-cpu variables to be page-aligned Ingo Molnar
2007-03-07  0:16               ` Rusty Russell
2007-03-07  0:44                 ` H. Peter Anvin
2007-03-06 18:17             ` Jeremy Fitzhardinge
2007-03-07  0:29               ` Rusty Russell
2007-03-06 18:16           ` [PATCH 5/8] Cleanup GDT access Jeremy Fitzhardinge
2007-03-06 18:14       ` [PATCH 3/8] Use per-cpu variables for GDT, PDA Jeremy Fitzhardinge
2007-03-06 13:21     ` [PATCH 2/8] Remove NR_CPUS from asm-generic/percpu.h Ingo Molnar
2007-03-06 13:20   ` [PATCH 1/8] Remove cpu_gdt_table: use boot_gdt_table until migration to per-cpu Ingo Molnar
2007-03-06 13:26     ` Ingo Molnar
2007-03-07  0:22     ` Rusty Russell [this message]
2007-03-13 20:48 ` [PATCH 0/8] x86 boot, pda and gdt cleanups Jeremy Fitzhardinge
2007-03-14  2:25   ` Rusty Russell
2007-03-14  4:39     ` Jeremy Fitzhardinge
2007-03-14  6:54       ` Rusty Russell
2007-03-14 23:55   ` Rusty Russell
2007-03-15  1:57     ` Jeremy Fitzhardinge

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