linux-kernel - Re: [PATCH RFC] x86: add brk allocation for very, very early allocations

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Message-ID: <49A858E8.3070707@goop.org>
Date:	Fri, 27 Feb 2009 13:19:36 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Yinghai Lu <yinghai@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	the arch/x86 maintainers <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] x86: add brk allocation for very, very early allocations

H. Peter Anvin wrote:
> That would make sense.  init_memory_mapping() needs to know what not to
> step on, and that would include the brk at this stage.  For 64-bit mode,
> Xen is the only user of !PSE, and so may be particularly vulnerable to
> this issue (because of massively larger direct mapping tables.)
>   

Yep.

> This reminds me... is your intent that the BRK is permanent (unless
> explicitly freed on a page by page basis) or part of the init memory
> that is flushed?
>   

Permanent.  I'm using it to allocate things which are the moral 
equivalent of the kernel pagetables.

    J
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