Re: [Qemu-devel] [PATCH] mark nic as trusted

[Jamie Lokier]

Daniel P. Berrange wrote:
> On Fri, Jan 09, 2009 at 01:14:33AM +0200, Dor Laor wrote:
> > Jamie Lokier wrote:
> > >Anthony Liguori wrote:
> > >  
> > >>Are we going to have a standard way of doing this in Linux distros such 
> > >>that these nics are treated differently from other nics?  Have we gotten 
> > >>the appropriate distro folks to agree to this?
> > >>    
> > >
> > >That wouldn't work for older distros and Windows anyway.  But you
> > >might reasonably want to run apps doing guest-host communication on
> > >older guest distros too, simply as an app, not requiring guest
> > >customisation.
> > >  
> > We can make fedora, rhel and libvirt support it. It might be a bit 
> > painful but since
> > a network device was chosen for this propose then that's the right way 
> > to go.
> 
> For new Fedora / RHEL yes, but a large number of people using virt are
> doing so with old OS versions, and the chances of anyone retro-fitting
> all old distros is near zero. You might get it done if they were back
> porting the VirtIO NIC devices to old distros, but almost certainly not
> for arbitrary NIC devices like rtl8139/e1000/etc because its a huge
> QA testing headache to avoid regressions.

In some circles, a major purpose of virtualisation is to run old OS
versions, either copied from machines where the hardware is aging to
keep a working system still working, or for compatibility testing.

Changing a working guest setup isn't cool.  Adding a small
monitoring/reporting app (e.g. that shows the machine's load average,
process table, network connections or whatever over a vmchannel) may
be cool, provided it has negligable impact, even if changing its
system configuration is not.

-- Jamie