State "bios" firmware support for OSes

[Felipe Borges]

Hi everyone,

We recently landed EFI support in GNOME Boxes where we create guests
with "firmware = efi" by default when libosinfo reports that the OS
supports it. This has worked great except for the regression with
snapshots. Long story short, internal snapshots won't work with EFI,
external snapshots won't allow our users to revert their domain to a
certain snapshot.

For this reason, the Boxes designers and I concluded that the best
approach for us here would be to only create EFI guests for OSes that
REQUIRE it. If an OS can still boot with the legacy "bios" we should
go for it, since it maintains our Snapshot management functionality.

The reason I am emailing libosinfo about this is to assess whether you
folk would be open to having me adding <firmware arch="x86_64"
type="bios"/> to the OSes that support it (some of them already state
support for EFI).

Since the API returns a list of Osinfo.Firmware objects, we won't need
any more work on libosinfo side in order to implement what we need in
Boxes.

All in all, adding <firmware arch="x86_64" type="bios"/> to some OSes
would be something you'd accept?

Cheers,
Felipe.