linux-kernel - Re: [PATCH 1/1 v1] the recommended crash memory reservation is too small for x86

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Message-ID: <51511C6A.1000001@redhat.com>
Date:	Tue, 26 Mar 2013 11:56:26 +0800
From:	WANG Chao <chaowang@...hat.com>
To:	周洲仪 <yizhouzhou@....ac.cn>
CC:	zhouzhouyi@...il.com, kexec@...ts.infradead.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	vgoyal@...hat.com
Subject: Re: [PATCH 1/1 v1] the recommended crash memory reservation is too
 small for x86_64.

On 03/25/2013 07:52 PM, 周洲仪 wrote:
> Thanks for reviewing
>   Is it sounds good to add following line into section "Boot into System Kernel":
> 
>   The memory reserved for crash kernel should be no less than the unpacked init ram disk size
> that loaded with dump-capture kernel plus wired memory used by kernel itself.

Sorry, that is just basic knowledge for everyone.

> 
>   #################
>   After all, I have been trapped into "hang after capture" problem when sticking strictly to this document.
> Cheers
> Zhouyi  
> 
>>  
>>  On 03/25/2013 06:56 PM, zhouzhouyi@...il.com wrote:
>>  > From: root <root@...-Lenovo.(none)>
>>  > 
>>  > 
>>  >  On Documentation/kdump/kdump.txt, section Boot into  System Kernel: On x86 and x86_64, use
>>  >  "crashkernel=64M@16M", but some OSes like ubuntu 12.10 use ram fs larger than 64M, so in these cases the
>>  >  memory reserved for crashkernel should be at least 128M.
>>  
>>  People use different initramfs generators for different purpose. That means
>>  the size of initramfs and also its memory consuming can vary very much from
>>  each other. You just can't list all these generators and their recommended
>>  reserved memory here. Though I have to say crashkernel=128M is good choice.
>>  
>>  I think it would be better to leave this to user or distribution itself to
>>  determine how much memory should be reserved for crash kernel, then export
>>  this value to kernel in some ways.
>>  
>>  Thanks,
>>  WANG Chao
>>  
>>  > 
>>  > 
>>  > Signed-off-by: Zhouyi Zhou <yizhouzhou@....ac.cn>
>>  > ---
>>  >  Documentation/kdump/kdump.txt |    4 +++-
>>  >  1 file changed, 3 insertions(+), 1 deletion(-)
>>  > 
>>  > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
>>  > index 13f1aa0..1e850e0 100644
>>  > --- a/Documentation/kdump/kdump.txt
>>  > +++ b/Documentation/kdump/kdump.txt
>>  > @@ -290,7 +290,9 @@ Boot into System Kernel
>>  >     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>>  >     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>>  >  
>>  > -   On x86 and x86_64, use "crashkernel=64M@16M".
>>  > +   On x86 and x86_64, use "crashkernel=64M@16M" (some OSes use init ram fs larger
>>  > +than 64M, for example ubuntu-12.10, use crashkernel=128M@16M instead, or dump-capture
>>  > +kernel will out of memory).
>>  >  
>>  >     On ppc64, use "crashkernel=128M@32M".
>>  >  
>>  > 
>>  
> 
> 
> 
> 

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