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Date: Mon, 09 Mar 2009 10:35:09 -0700
From: Yinghai Lu <yinghai@kernel.org>
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: put initial_pg_tables into .bss -v4
References: <1235785882-17580-1-git-send-email-jeremy@goop.org> <1235785882-17580-4-git-send-email-jeremy@goop.org> <86802c440902272302n3787b2bex3741b46a372a19b0@mail.gmail.com> <49A8E235.6010900@goop.org> <20090228071534.GB9351@elte.hu> <49A8EA1A.50802@kernel.org> <49A8ED3D.1060704@kernel.org> <49A8F319.3030802@goop.org> <49A9E392.6090004@kernel.org> <49AA47D2.4020804@kernel.org> <49AA5356.3050602@zytor.com> <49AACEB3.5050206@kernel.org> <49AB1A5C.6040300@zytor.com> <49AB2E69.1010201@kernel.org> <49B4D03D.7030205@kernel.org> <49B538AB.9080006@zytor.com>
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H. Peter Anvin wrote:
> Yinghai Lu wrote:
>> Impact: cleanup
>>
>> Don't use ram after _end blindly for pagetables. aka init pages is before _end
>> put those pg table into .bss
>>
>> v2: keep initial page table up to 512M only.
>> v4: put initial page tables just before _end
>>
>> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>>
> 
> I still feel that this is a movement in *EXACTLY* the wrong direction,
> as it is deliberately intended to prevent a general allocator for
> anything that needs to be dynamic very early on.  I still think that
> makes a lot more sense.

it just estimates initial_pg_tables size, and make _end a little bigger (1M), so boot loader could have idea of correct size of vmlinux aka the uncompressed size of in kernel.

I assume brk patches could estimate the extra size that it needs too.

YH