Re: [PATCH ndctl v2 0/7] cxl: add support for listing and creating volatile regions

[Dan Williams <dan.j.williams@intel.com>]

Brice Goglin wrote:
[..]
> >> By the way, once configured in system ram, my CXL ram is merged into an
> >> existing "normal" NUMA node. How do I tell Qemu that a CXL region should
> >> be part of a new NUMA node? I assume that's what's going to happen on
> >> real hardware?
> > We don't yet have kernel code to deal with assigning a new NUMA node.
> > Was on the todo list in last sync call I think.
> 
> 
> Good to known, thanks again.

In fact, there is no plan to support "new" NUMA node creation. A node
can only be onlined / populated from set of static nodes defined by
platform-firmware. The set of static nodes is defined by the union of
all the proximity domain numbers in the SRAT as well as a node per
CFMWS / QTG id. See:

    fd49f99c1809 ACPI: NUMA: Add a node and memblk for each CFMWS not in SRAT

...for the CXL node enumeration scheme.

Once you have a node per CFMWS then it is up to CDAT and the QTG DSM to
group devices by window. This scheme attempts to be as simple as
possible, but no simpler. If more granularity is necessary in practice,
that would be a good discussion to have soonish.. LSF/MM comes to mind.