On 28/08/2025 8:07 am, Jan Beulich wrote: > On 27.08.2025 19:47, Andrew Cooper wrote: >> On 22/08/2025 2:47 pm, Teddy Astie wrote: >>> Currently, hvmloader uses SMBIOS 2.4, however, when using OVMF, the >>> SMBIOS is patched to 2.8, which has clarified the UUID format (as GUID). >>> >>> In Linux, if the SMBIOS version is >= 2.6, the GUID format is used, else >>> (undefined as per SMBIOS spec), big endian is used (used by Xen). Therefore, >>> you have a endian mismatch causing the UUIDs to mismatch in the guest. >>> >>> $ cat /sys/hypervisor/uuid >>> e865e63f-3d30-4f0b-83e0-8fdfc1e30eb7 >>> $ cat /sys/devices/virtual/dmi/id/product_uuid >>> 3fe665e8-303d-0b4f-83e0-8fdfc1e30eb7 >>> $ cat /sys/devices/virtual/dmi/id/product_serial >>> e865e63f-3d30-4f0b-83e0-8fdfc1e30eb7 >>> >>> This patch updates the SMBIOS version from 2.4 to 2.6 and fixup the UUID >>> written in the table; which effectively fix this endianness mismatch with >>> OVMF; while the UUID displayed by Linux is still the same for SeaBIOS. >>> >>> Signed-off-by: Teddy Astie <teddy.as...@vates.tech> >>> --- >>> This effectively changes the UUID seen with UEFI guests as it was >>> actually inconsistent with SeaBIOS and SMBIOS expectations. >>> --- >> I agree this is a real bug and needs fixing. > Hmm, I didn't realize this is a bug, and hence put the patch off as 4.22 > material. If there is a bug being fixed: Teddy, please add a Fixes: tag.
I'm not sure if this has a reasonable Fixes tag. It's a combination of an ill-specified domain handle format, and using an ill-specified version of the SMBios spec. ~Andrew
