linux-kernel - Re: [GIT PULL] x86: add brk allocator for very early allocations

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Date:	Fri, 13 Mar 2009 15:45:36 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	Yinghai Lu <yinghai@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	the arch/x86 maintainers <x86@...nel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] x86: add brk allocator for very early allocations

Jeremy Fitzhardinge wrote:
>>>
>>> INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE +
>>> ALLOCATOR_SLOP)*PAGE_SIZE_asm
>>>     
>>
>> no user for INIT_MAP_BEYOND_END any more.
>>   
> 
> There are several remaining references:
> 
> : abulafia:pts/0; grep INIT_MAP_BEYOND_END arch/x86/kernel/head_32.S 
> INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + 
> ALLOCATOR_SLOP)*PAGE_SIZE_asm
> * and PAGE_OFFSET for up to _end+sizeof(page tables)+INIT_MAP_BEYOND_END.
>      * End condition: we must map up to and including INIT_MAP_BEYOND_END
>     leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp
>      * End condition: we must map up to and including INIT_MAP_BEYOND_END
>     leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp
> 
> Are you saying they're redundant and should be removed?
> 

Those references are just the actual reservation of memory.  If all the 
users of that memory are converted to either brk or bss, 
INIT_MAP_BEYOND_END should be removed.  If all the users of that memory 
aren't converted to brk to bss, we should do so.

	-hpa
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