bug#31365: libvirt/virt-manager: Embeds full path to qemu-system in saved .xml files

[iyzsong@member.fsf.org (宋文武)]

Vagrant Cascadian <vagrant@debian.org> writes:

> When i create a new libvirt instance with virt-manager, it embeds the
> full path to the qemu binary used at the time. For the machine named
> "networkboot":
>
>   # grep qemu-system /etc/libvirt/qemu/networkboot.xml
>   <emulator>/gnu/store/0rzb7rjri2kb258j58asndw2pnp0xv9p-qemu-2.11.1/bin/qemu-system-x86_64:</emulator>
>
> If I later run "guix gc" and it happens to remove this particular qemu
> version, the system no longer runs, of course:
>
>   # virsh start networkboot
>   error: Failed to start domain networkboot
>   error: Cannot check QEMU binary
>       /gnu/store/0rzb7rjri2kb258j58asndw2pnp0xv9p-qemu-2.11.1/bin/qemu-system-x86_64:
>       No such file or directory
>
> It also means each virtual machine may be running on an older version of
> qemu, for better or worse.
>
> Manaully replacing the emulator entry in the .xml file with
> /run/current-system/profie/bin/qemu-system-x86_64 works around the
> issue, and might be the easiest fix.
>

Hello, I believe my commit 'ef640db2f509f51ebfe3a6a66ba837ef3103bbb7'
fix this, now it use '/run/current-system/profie/bin/qemu-system-x86_64'
in the xml files.  Close now..  Thank you!