Re: [PATCH v6 0/1] numa: add 'memmap-type' option for memory type configuration

[Jonathan Cameron via qemu development <qemu-devel@nongnu.org>]

On Thu, 26 Feb 2026 18:50:22 +0800
fanhuang <FangSheng.Huang@amd.com> wrote:

> Hi all,
> 
> This is v6 of the SPM (Specific Purpose Memory) patch. Thank you for
> the feedback on v5, especially Gregory's review.
> 
> Changes in v6:
> - Added validation: memmap-type now requires memdev to be specified,
>   to avoid misconfiguration on memory-less NUMA nodes
> - Simplified pc_update_numa_memory_types() by replacing switch/goto
>   with a direct conditional expression
> - Reserved memory nodes are now excluded from SRAT memory affinity
>   entries, since E820 already marks them as reserved and SRAT should
>   not report them as enabled memory affinity
> 
> Use case:
> This feature allows marking NUMA node memory as Specific Purpose Memory
> (SPM) or reserved in the E820 table. SPM serves as a hint to the guest
> that this memory might be managed by device drivers based on guest policy
> 
> Example usage:
>   -object memory-backend-ram,size=8G,id=m0
>   -object memory-backend-memfd,size=8G,id=m1
>   -numa node,nodeid=0,memdev=m0
>   -numa node,nodeid=1,memdev=m1,memmap-type=spm
> 
> Supported memmap-type values:
>   - normal:   Regular system RAM (E820 type 1, default)
>   - spm:      Specific Purpose Memory (E820 type 0xEFFFFFFF), a hint
>               that this memory might be managed by device drivers
>   - reserved: Reserved memory (E820 type 2), not usable as RAM
Interface looks good to me.  I'm not familiar enough to confirm the
x86 specific elements without more time than I have today though so
no tags from me.

Thanks for doing this! 

Jonathan