Hi all,

This is v4 of the SPM (Specific Purpose Memory) patch. Thank you Jonathan
for the detailed review.

Changes in v4 (addressing Jonathan's feedback):
- Added architecture check: spm=on now reports error on non-x86 machines
- Simplified return logic in e820_update_entry_type() (return true/false directly)
- Changed 4GB boundary spanning from warn_report to error_report + exit
- Updated QAPI documentation to be architecture-agnostic (removed E820 reference)
- Removed unnecessary comments

Use case:
This feature allows passing EFI_MEMORY_SP (Specific Purpose Memory) from
host to guest VM, useful for memory reserved for specific PCI devices
(e.g., GPU memory via VFIO-PCI). The SPM memory appears as soft reserved
to the guest and is managed by device drivers rather than the OS memory
allocator.

Example usage:
  -object memory-backend-ram,size=8G,id=m0
  -object memory-backend-file,size=8G,id=m1,mem-path=/dev/dax0.0
  -numa node,nodeid=0,memdev=m0
  -numa node,nodeid=1,memdev=m1,spm=on

Please review. Thanks!

Best regards,
Jerry Huang

-- 
2.34.1