[PATCH 1/3] MIPS: Crash kernel should be able to see old memories

[Maciej W. Rozycki]

On Wed, 23 Sep 2020, Baoquan He wrote:

> > > And we don't have mem=X at Y, only mem=nn[KMG].
> > The relocatable kernel of MIPS is still unusable now, so MIPS should
> > use mem=X at Y, and the crash kernel is always different from normal
> > kernel.
> 
> Interesting. Seems MIPS does support mem=X at Y, even though the document
> of 'mem=' says it's used to specify amount of memory, but not memory
> region. Anyway, leave this to mips reviewers, thanks for replying.
> 
> ~~~~~~~~~~~~~~~~~~~
>         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
>                         Amount of memory to be used in cases as follows:

 Yep, I implemented it for the DECstation back in 2000:

commit 97b7ae4257ef7ba8ed9b7944a4f56a49af3e8abb
Author: Ralf Baechle <ralf at linux-mips.org>
Date:   Mon Dec 11 16:41:05 2000 +0000

    Memmap fixes from Maciej.

(from the LMO repo) in line with the x86 syntax.  I don't know why it 
hasn't ever been documented in "Kernel Parameters" (for any port), but I'm 
fairly sure it has been somewhere.

 FWIW,

  Maciej