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

[Jamie Lokier]

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.

Is there some way to mark a PCI device so it will be ignored at boot
time generically?  Changing the PCI ID will do that for all guests,
but is it then feasible for the vmchannel guest admin software to bind
a NIC driver to a non-standard PCI ID, on the major OSes?

Suppose you start a guest with two "trusted" nics, because you want to
run two unrelated vmchannel-using admin apps.  How does each app know
which nic to use - or do they share it?

As the guest OS's TCP is being used, what do you do about IP address
space conflicts?

I.e. if NIC #1 is the guest's LAN, and NIC #2 is the vmchannel, how is
the vmchannel NIC going to be configured in a way that's guaranteed to
avoid breaking the LAN networking, which could be assigned any legal
subnet (especially when bridging is used), and on some networks
changes from time to time?

Perhaps vmchannel will only use IPv6, so it can confidently pick a
unique link-local address?

-- Jamie