Re: [LSF/MM/BFP TOPIC] Deprecate SPARSEMEM and have only SPARSEMEM_VMEMMAP

[Mike Rapoport <rppt@kernel.org>]

On Mon, May 13, 2024 at 11:43:09AM +0200, Oscar Salvador wrote:
> On Fri, May 10, 2024 at 11:03:58PM +0100, Matthew Wilcox wrote:
> > I'm a little concerned about having this conversation without the
> > affected architecture maintainers in the room.  However, I can speak to
> > PA-RISC.
> 
> Yes, having the architecture maintainers would be great.
> 
> > Early models have a dense memory layout and we need not be concerned
> > with them.  I'm not quite sure about the PA-7200 to PA-8500 ccio based
> > machines, would need to do some research.  For the PA-8500+ astro based
> > machines, the 256MB that would be in the range 3.75GB to 4GB is
> > relocated to 67.75-68GB to leave space for PCI mmio.  So if you have
> > a machine with 8GB of memory (fairly typical for a J6000 machine),
> > you'd have three ranges of memory:
> > 
> > 0-3.75GB
> > 4-8GB
> > 67.75-68GB
> > 
> > and I'd like to see an analysis of how laying out memmap would differ
> > for those machines.
> 
> Maybe Mike can prove me wrong, but I assume that memblock will report
> the above ranges as memory, and the 3.75GB to 4GB as somewhat reserved.

The populated ranges will be reported as memory and it seems that there
just will be a hole at the 3.75GB-4GB range. Not that it's important from
the sections layout perspective.

> -- 
> Oscar Salvador
> SUSE Labs
> 

-- 
Sincerely yours,
Mike.