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From: Rusty Russell <>
To: Andi Kleen <>
Cc: Jeremy Fitzhardinge <>,
	Andrew Morton <>,,
	lkml <>
Subject: Re: [patch 4/6] Convert PDA into the percpu section
Date: Sat, 31 Mar 2007 12:54:17 +1000	[thread overview]
Message-ID: <1175309657.12230.420.camel@localhost.localdomain> (raw)
In-Reply-To: <>

On Sat, 2007-03-31 at 04:35 +0200, Andi Kleen wrote:
> On Saturday 31 March 2007 04:00, Jeremy Fitzhardinge wrote:
> > Currently x86 (similar to x84-64) has a special per-cpu structure
> > called "i386_pda" which can be easily and efficiently referenced via
> > the %fs register.  An ELF section is more flexible than a structure,
> > allowing any piece of code to use this area.  Indeed, such a section
> > already exists: the per-cpu area.
> Hmm, I'm a little reluctant. This moves i386 more away from x86-64
> again. If we ever merge them it would mean more work. Do you really need it?

Well, I think the merge should go the other way in this case: this
really does simplify things.

The only thing stopping x86-64 from doing the same as i386 is the
stack-protector stuff.  And that can be fixed (unfortunately requires a
gcc patch to change the %gs:40 to %gs:__gcc_stack_protector_offset and
emit a weak absolute symbol __gss_stack_protector_offset = 40).

I shall prepare a patch for that next week; I've been busy Kleening up
lguest 8)


  reply	other threads:[~2007-03-31  2:54 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-31  2:00 [patch 0/6] i386 gdt and percpu cleanups Jeremy Fitzhardinge
2007-03-31  2:00 ` [patch 1/6] i386: Account for module percpu space separately from kernel percpu Jeremy Fitzhardinge
2007-03-31  2:00 ` [patch 2/6] Allow percpu variables to be page-aligned Jeremy Fitzhardinge
2007-03-31  2:00 ` [patch 3/6] Page-align the GDT Jeremy Fitzhardinge
2007-03-31  2:00 ` [patch 4/6] Convert PDA into the percpu section Jeremy Fitzhardinge
2007-03-31  2:35   ` Andi Kleen
2007-03-31  2:54     ` Rusty Russell [this message]
2007-03-31  3:00     ` Jeremy Fitzhardinge
2007-03-31  2:00 ` [patch 5/6] cleanups to help using per-cpu variables from asm Jeremy Fitzhardinge
2007-03-31  2:00 ` [patch 6/6] Define per_cpu_offset Jeremy Fitzhardinge
2007-03-31  2:56 ` [patch 0/6] i386 gdt and percpu cleanups Rusty Russell
2007-03-31  3:05   ` Jeremy Fitzhardinge
2007-03-31  3:16 ` Jeremy Fitzhardinge

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