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

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Message-ID: <AANLkTilNXcS_KQTQ4ZwDt8RQqSrlWUH2R5W87g0vI4xG@mail.gmail.com>
Date:	Wed, 26 May 2010 10:39:24 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Mike Travis <travis@....com>
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.

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
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