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

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Message-ID: <4BEAF9B6.2040606@zytor.com>
Date:	Wed, 12 May 2010 11:55:50 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Mike Travis <travis@....com>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	x86@...nel.org, Yinghai Lu <yinghai@...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>
Subject: Re: [Patch 1/1] x86 efi: Fill all reserved memmap entries if add_efi_memmap
 specified.

On 05/12/2010 11:10 AM, Mike Travis wrote:
> 
> Currently, the e820_reserve_resources() function does not add entries
> obtained via the "add_efi_memmap" kernel cmdline option.  This causes
> /sys/firmware/memmap/... to be incomplete (stops after 128 entries).
> Utilities that examine these entries then do not get the complete
> picture of system memory.
> 
> This patch causes the above function to use the e820 memmap instead
> of the e820_saved memmap if "add_efi_memmap" cmdline option is
> specified.
> 
> Signed-off-by: Mike Travis <travis@....com>
> Signed-off-by: Jack Steiner <steiner@....com>

If I'm not mistaken, the very reason for the e820 vs e820_saved map is
that the latter is supposed to reflect the firmware report, whereas the
former is subject to be modified by the kernel.  As this is actually a
reflection of the firmware (although it would be better if you could fix
the bootloader instead of adding hacks in the kernel...) it really
should go into e820_saved as well as e820.  Displaying the adjusted e820
map doesn't seem appropriate under any circumstances.

	-hpa
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