Re: [PATCH] x86, kdump: Set crashkernel_low automatically

[Vivek Goyal <vgoyal@redhat.com>]

On Mon, Mar 11, 2013 at 12:06:06PM -0700, Yinghai Lu wrote:

[..]
> > I actually disagree with trying low memory at all.  Push kdump as high
> > into the memory range as we can go, if there is a performance penalty it
> > is much better to take it in the kdump kernel.
> 
> Agreed, It's better let 64 bit all use one code path.
> And we can find more bugs while load them all high.
> otherwise it would be hard to fix them if the bugs only happens on systems
> that have bunch of dimms.

I find it odd that if a user wants to load a 32bit kernel or use 32bit
entry point then he needs to first reboot the kernel and re-reserve
the memory.

At installation time, one does not necessarily know what kind of kernel
will be used for crashdump. So reserving as high as possible limits
the choices.

I would rather prefer that user opt in for higher addresses instead of
these being reserved by default.

Thanks
Vivek