[PATCH -next] Documentation: Improve crashkernel= description

[WANG Cong]

On Sun, 06 Feb 2011 20:25:20 -0600, Rob Landley wrote:

> 
> Suitable offset as in parses a known image type (ELF, bzImage, etc) to
> find the start address?  Or just assumes the entry point and load
> address are the same?


No, that is the start physical address of crashkernel, which should be
your system RAM not reserved by your BIOS etc..

The beginning of the physical memory is often fragmented, thus specifying 
a fixed offset may not work on a specific machine.

> 
> Is this the size for just the kernel image, or also for the physical
> memory it uses so it won't overwrite the existing kernel's stuff on the
> way up?  (If a compressed kernel wants to decompress itself or extract
> an initramfs for itself, what happens?)
> 

The size means the whole physical memory size available to the second
kernel (i.e. crash kernel), which includes the memory occupied by 
vmlinuz, initrd, *and* the memory which will be used by the programs
inside initrd (e.g. /sbin/init). If this memory is not sufficient,
you will get OOM.