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

[周洲仪]

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.

  #################
  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 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".
> >  
> > 
>