linux-kernel - Re: [PATCH 2/2] x86 e820: Introduce memmap=resetusablemap for kdump usage

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Date:	Mon, 28 Jan 2013 18:10:38 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Thomas Renninger <trenn@...e.de>, x86@...nel.org,
	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	vgoyal@...hat.com, horms@...ge.net.au
Subject: Re: [PATCH 2/2] x86 e820: Introduce memmap=resetusablemap for kdump usage

On Mon, Jan 28, 2013 at 5:11 PM, H. Peter Anvin <hpa@...or.com> wrote:
>> So I guess the final patch should be:
>>    - Add a new e820 type:
>>         E820_KDUMP_RESERVED /* Originally usable memory where the crashed
>>                                                     kernel kernel resided in */
>>   - Use Yinghai's last posted patch, but instead of:
>> +                     e820_update_range(0, ULLONG_MAX, E820_RAM,
>> +                                       E820_RESERVED);
>> ...
>> +                     e820_remove_range(start_at, mem_size, E820_RESERVED, 0);
>> do:
>> +                     e820_update_range(0, ULLONG_MAX, E820_RAM,
>> +                                       E820_KDUMP_RESERVED);
>> ...
>> +                     e820_remove_range(start_at, mem_size, E820_KDUMP_RESERVED, 0);
>>
>>   - Come up with another memmap=kdump_reserve_ram memmap option name
>>     or however it should get named...
>>
>> If this proposal gets accepted, I can send a tested patch...
>>
>
> Yes, this is much saner.  There really shouldn't need to be an option,
> even; since the tools need to be modified anyway, just modify the actual
> memory map data structure itself.

yes,

kexec-tools will change that to E820_KDUMP_RESERVED (or other good name).

We only need to update kernel to get old max_pfn by
checking E820_KDUMP_RESERVED.

Yinghai
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