[Pkg-libvirt-maintainers] Bug#966239: please drop `qemu' from Recommends|Enhances

[Michael Tokarev]

Package: libvirt-daemon
Version: 5.0.0-4+deb10u1
Severity: minor

qemu is a dummy metapackage which has no actual reason to exist.
Qemu provides 2 entirely different modes of operations, it is a
system-level emulation, where qemu emulates whole (hardware)
system with its own CPU, memory subsystem, peripherial devices,
BIOS/firmware etc. This is qemu-system, or, with hardware
assistance, qemu-kvm. And another mode, where it can run
linux programs built for different architecture on another
linux system, for example to run arm linux binaries on an
x86 linux. This is qemu-user and variations.

libvirt enhances the first mode, i.e. system emulation, and
has nothing to do with the second, linux-user, emulation of
qemu.

It is enough, I think, to Recommend/Ehnance qemu-kvm, --
which is qemu with hardware-assisted system emulation,
which is almost-native (for a given CPU) variant.
We in qemu added Provides: qemu-kvm for a few packages
where it is appropriate, - for example, on x86_64 it
is qemu-system-x86 package, on s390x it is the package
with qemu-system-s390x binary (which again can do native
emulation of a s390x system) and so on.

The goal is to remove `qemu' binary metapackage from
Debian, because this package is not right, it is
pulling whole qemu with all its modes of operations, -
this is not what most people actually want, due to
what's been said above.

If libvirt can run foreigh architectures too, we can
declare that it enhances qemu-system package (which
too is a meta-package but it is more meaningful that
just qemu). Or even better in this case, libvirt can
enhance all other qemu-system-XXX packages (XXX being
arm, misc, mips, ppc, sparc, s390x and x86) - because
qemu-system by itself can't be enhanced (just like
qemu), and it can suggest qemu-system. But it definitely
should not Recommend: whole qemu.

Thanks,

/mjt