[PATCH 1/1 v1] the recommended crash memory reservation is too small for x86_64.

[WANG Chao]

On 03/25/2013 06:56 PM, zhouzhouyi at gmail.com wrote:
> From: root <root at zzy-Lenovo.(none)>
> 
> 
>  On Documentation/kdump/kdump.txt, section Boot into  System Kernel: On x86 and x86_64, use
>  "crashkernel=64M at 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 at ict.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 at 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 at 16M".
> +   On x86 and x86_64, use "crashkernel=64M at 16M" (some OSes use init ram fs larger
> +than 64M, for example ubuntu-12.10, use crashkernel=128M at 16M instead, or dump-capture
> +kernel will out of memory).
>  
>     On ppc64, use "crashkernel=128M at 32M".
>  
>