edk2 passes no -march for the X64 toolchains, so the ISA baseline of the
shipped firmware is whatever the builder's GCC defaults to, and AlmaLinux 10
builds GCC with --with-arch_64=x86-64-v3. edk2-ovmf is noarch and one build
is shared by the x86_64 and the x86_64_v2 repositories, so OVMF ends up
carrying BMI1/BMI2 code and no UEFI guest boots on a v2-only CPU: it resets
in a loop right after the SEC phase.
%{optflags} cannot fix this. edk2.spec exports it as EXTRA_OPTFLAGS, which
only reaches the host BaseTools binaries, and edk2-build.py has no way to
pass compiler flags to the firmware build, so tools_def is the only place
where the baseline can be set.
The same patch applies to both edk2 snapshots (a10: 20251114/46548b1adac8,
a10s: 20260221/b7a715f7c03c) - the context around the define is identical.
rpms/edk2#1
82c66f1853