linux-kernel - Re: [PATCH] mm: Introduce kernelcore=reliable option

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Date:	Tue, 20 Oct 2015 09:42:23 +0800
From:	Xishi Qiu <qiuxishi@...wei.com>
To:	"Izumi, Taku" <izumi.taku@...fujitsu.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	"Kamezawa, Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>,
	"mel@....ul.ie" <mel@....ul.ie>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"dave.hansen@...el.com" <dave.hansen@...el.com>,
	"matt@...eblueprint.co.uk" <matt@...eblueprint.co.uk>
Subject: Re: [PATCH] mm: Introduce kernelcore=reliable option

On 2015/10/20 8:34, Izumi, Taku wrote:

>  Hi Xishi,
> 
>> On 2015/10/15 21:32, Taku Izumi wrote:
>>
>>> Xeon E7 v3 based systems supports Address Range Mirroring
>>> and UEFI BIOS complied with UEFI spec 2.5 can notify which
>>> ranges are reliable (mirrored) via EFI memory map.
>>> Now Linux kernel utilize its information and allocates
>>> boot time memory from reliable region.
>>>
>>> My requirement is:
>>>   - allocate kernel memory from reliable region
>>>   - allocate user memory from non-reliable region
>>>
>>> In order to meet my requirement, ZONE_MOVABLE is useful.
>>> By arranging non-reliable range into ZONE_MOVABLE,
>>> reliable memory is only used for kernel allocations.
>>>
>>> This patch extends existing "kernelcore" option and
>>> introduces kernelcore=reliable option. By specifying
>>> "reliable" instead of specifying the amount of memory,
>>> non-reliable region will be arranged into ZONE_MOVABLE.
>>>
>>> Earlier discussion is at:
>>>  https://lkml.org/lkml/2015/10/9/24
>>>
>>
>> Hi Taku,
>>
>> If user don't want to waste a lot of memory, and he only set
>> a few memory to mirrored memory, then the kernelcore is very
>> small, right? That means OS will have a very small normal zone
>> and a very large movable zone.
> 
>  Right.
> 
>> Kernel allocation could only use the unmovable zone. As the
>> normal zone is very small, the kernel allocation maybe OOM,
>> right?
> 
>  Right.
> 
>> Do you mean that we will reuse the movable zone in short-term
>> solution and create a new zone(mirrored zone) in future?
> 
>  If there is that kind of requirements, I don't oppose 
>  creating a new zone.
> 

As far as I know, some apps(e.g. date base) maybe could only use
the normal zone.

Thanks,
Xishi Qiu

>  Sincerely,
>  Taku Izumi
> 
> .
> 



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