Re: [PATCH v4 2/2] dax/kmem: allow kmem to add memory with memmap_on_memory

[Verma, Vishal L]

On Tue, 2023-10-03 at 09:34 +0530, Aneesh Kumar K V wrote:
> On 9/29/23 2:00 AM, Vishal Verma wrote:
> > Large amounts of memory managed by the kmem driver may come in via CXL,
> > and it is often desirable to have the memmap for this memory on the new
> > memory itself.
> > 
> > Enroll kmem-managed memory for memmap_on_memory semantics if the dax
> > region originates via CXL. For non-CXL dax regions, retain the existing
> > default behavior of hot adding without memmap_on_memory semantics.
> > 
> 
> Are we not looking at doing altmap space for CXL DAX regions? Last discussion around
> this was suggesting we look at doing this via altmap reservation so that
> we get contigous space for device memory enabling us to map them
> via 1G direct mapping entries? 
> 
Hey Aneesh - was this on a previous posting or something - do you have
a link so I can refresh myself on what the discussion was?

If it is enabling something in CXL similar to the --map=mem mode for
pmem + device dax, that could be incremental to this.