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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Brian Gerst <brgerst@gmail.com>
Cc: Tejun Heo <htejun@gmail.com>, Ingo Molnar <mingo@elte.hu>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: unified percpu stuff
Date: Tue, 27 Jan 2009 09:50:58 -0800	[thread overview]
Message-ID: <497F4982.8060103@goop.org> (raw)
In-Reply-To: <73c1f2160901270435t5623b0d8tbf832b1f8a575b2e@mail.gmail.com>

Brian Gerst wrote:
>> BTW, does the initial cpu0 percpu area get reallocated and moved during
>> boot, or does cpu0 keep using the same memory forever?
>>     
>
> It is reallocated in setup_per_cpu_areas().
>   

Hm, OK.  What's the reason we need to move cpu 0's percpu area?  Its 
always seemed a bit awkward.

Once it has been moved, how can I find the address of a variable in the 
original boot-time cpu 0 percpu area?  There's a couple of pages which 
Xen will have marked RO which need to be made RW if they're being freed 
back into the kernel pool.  Currently I use per_cpu_var(gdt_page), but 
guess that's a small offset rather than a directly usable address.

Thanks,
    J

  reply	other threads:[~2009-01-27 17:51 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-27  1:12 unified percpu stuff Jeremy Fitzhardinge
2009-01-27  4:17 ` Tejun Heo
2009-01-29 10:43   ` Jeremy Fitzhardinge
2009-01-29 11:01     ` Tejun Heo
2009-01-29 13:43     ` [PATCH] x86: pass in cpu number to switch_to_new_gdt() Brian Gerst
2009-01-29 21:36       ` Jeremy Fitzhardinge
2009-01-29 21:36       ` [PATCH 1/2] x86: split loading percpu segments from loading gdt Jeremy Fitzhardinge
2009-01-29 21:36       ` [PATCH 2/2] xen: setup percpu data pointers Jeremy Fitzhardinge
2009-01-30  8:50         ` Tejun Heo
2009-01-30  8:50       ` [PATCH] x86: pass in cpu number to switch_to_new_gdt() Tejun Heo
2009-01-27  5:57 ` unified percpu stuff Brian Gerst
2009-01-27  7:24   ` Jeremy Fitzhardinge
2009-01-27 12:35     ` Brian Gerst
2009-01-27 17:50       ` Jeremy Fitzhardinge [this message]
2009-01-27 19:07         ` Brian Gerst

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