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Date: Mon, 16 Mar 2009 13:26:38 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Jeremy Fitzhardinge <jeremy@goop.org>
CC: Yinghai Lu <yinghai@kernel.org>, Ingo Molnar <mingo@elte.hu>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [crash] Re: Latest brk patchset
References: <49BC413B.5020104@zytor.com> <49BC4CAC.202@goop.org> <49BC4DB6.9070403@zytor.com> <49BCA03D.3020605@goop.org> <20090315203802.GA14625@elte.hu> <49BD70EF.7010204@goop.org> <20090315212854.GA23960@elte.hu> <49BD8F15.4020301@goop.org> <20090316085402.GC1062@elte.hu> <49BE7A84.2030503@goop.org> <49BE84D6.3010006@kernel.org> <49BE9248.6050707@goop.org> <49BE97D5.4010002@zytor.com> <49BEA7BE.6050400@goop.org> <49BEAD27.3050801@kernel.org> <49BEAFEC.7020400@goop.org>
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Jeremy Fitzhardinge wrote:
> Yinghai Lu wrote:
>>> -INIT_MAP_SIZE = (PAGE_TABLE_SIZE + ALLOCATOR_SLOP) * PAGE_SIZE_asm
>>> -RESERVE_BRK(pagetables, INIT_MAP_SIZE)
>>> +/* Enough space to fit pagetables for the low memory linear map */
>>> +MAPPING_BEYOND_END = (PAGE_TABLE_SIZE(1 << (32 - PAGE_SHIFT)) * 
>>> PAGE_SIZE)
>>>     
>>
>> that is for 4g?
>>   
> 
> Yes, I suppose it only needs to be 1G.  But it doesn't make much 
> difference in practice.
> 

A tighter bound would probably be nice, if nothing else because tighter 
bounds tend to catch more bugs.

	-hpa