[libvirt] problems with current libvirt and qemu-kvm

[Eric Blake]

> So I downgraded to a previous version that I knew worked and it did
> but
> my RTR-ADVERT messages are back.  The "good" version uses a tarball
> created from git on November 19th and the "bad" version has a tarball
> created from git on November 29th.

Have you ever used 'git bisect' before?  It makes the task of whittling
down to an offending commit very easy, particularly if you can write
a shell script that will automate the steps needed to prove if the
bug is present for that particular git commit when you have two other
known commits where one is bad and the other is good.

'man git-bisect', and look at the details about 'bisect run'.

Meanwhile, are you comfortable using gdb?  The error message of
"internal error cannot find suitable emulator for X86_64." seems
like it occurs early enough in the startup that it should be
possible to find the function that prints that message, stick
a gdb breakpoint at the start of that function, run libvirtd,
and inspect the backtrace, to at least get an idea of what file
and its callers are worth narrowing down on your search for a
culprit that prevent you from using latest git sources.

Alas, I'm not having any problems using qemu-kvm from a just-built
libvirt.git on my machine, so I'm not sure why it is failing for
you.