linux-kernel - Re: [Patch 1/1] x86 efi: Fill all reserved memmap entries if add_efi

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Message-ID: <4BFD5D98.6090408@sgi.com>
Date:	Wed, 26 May 2010 10:42:48 -0700
From:	Mike Travis <travis@....com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Jens Axboe <jens.axboe@...cle.com>,
	Jack Steiner <steiner@....com>,
	LKML <linux-kernel@...r.kernel.org>, jkosina@...ell.com
Subject: Re: [Patch 1/1] x86 efi: Fill all reserved memmap entries if 	add_efi_memmap
 specified.



Yinghai Lu wrote:
> On Tue, May 25, 2010 at 3:46 PM, Mike Travis <travis@....com> wrote:
>>
>> H. Peter Anvin wrote:
>>> On 05/25/2010 03:34 PM, Mike Travis wrote:
>>>> H. Peter Anvin wrote:
>>>>> On 05/13/2010 02:55 PM, Mike Travis wrote:
>>>>>> I saw that too, and wondered why e820_saved did not
>>>>>> have the extra entries.   The comment indicates it
>>>>>> should.
>>>>>>
>>>>>> I'm on the system tonight and will investigate this
>>>>>> further.
>>>>>>
>>>>> e820_saved lacks the extra entries because they aren't being passed in
>>>>> from the bootloader, as they should, and instead you're using
>>>>> add_efi_memmap which is, as far as the kernel is concerned, a post-boot
>>>>> modification.
>>>>>
>>>>> That being said, add_efi_memmap does come from the firmware, and as such
>>>>> it would be legitimate for it to add them to e820_saved.
>>>>>
>>>>>        -hpa
>>>> Did this last patch meet expectations?
>>>>
>>>> http://marc.info/?l=linux-kernel&m=127474230623061&w=4
>>>>
>>> I'm concerned about calling sanitize_e820_map() on e820_saved; it is
>>> supposed to reflect the raw data as reported by the source, and
>>> sanitizing it would corrupt that.
>>>
>>>        -hpa
>> I wondered about that. Sanitize seems to remove adjacent
>> entries, etc. making the map smaller, but I couldn't detect
>> any real differences (though admittedly I didn't do a byte
>> by byte comparison.)
>>
>> But I'll submit another with that call removed.
> 
> can you use updated boot loader instead?
> 
> Also we should drop add_efi_memmap if possible.
> 
> YH

I'm open for suggestions on how to improve this, but we are shipping
systems very soon and I don't think we'll get any other change into
the system until the next update.

Thanks,
Mike
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