Anthony Liguori wrote:
> Avi Kivity wrote:
> >>+int net_init_bridge(QemuOpts *opts, Monitor *mon, const char *name,
> >>VLANState *vlan);
> >>+
> >>
> >
> >Don't we need to tear the interface down after shutdown?
>
> net_init_bridge calls net_tap_fd_init which registers tap_cleanup. That
> closes the fd and frees associated memory.
>
> The helper does not allocate a persistent tap device so closing the file
> descriptor is sufficient for cleanup.
I think you should at least have the option to call a/the helper when
cleaning up too.
For the same reason that -net downscript= was added. (From the names
I get the impression that was added later than -net script=, perhaps
due to the same kind of oversight ;-)
A user-supplied helper (I'm thinking of my needs) would create per-tap
iptables/ebtables rules and perhaps routing table entries, in addition
to creating the tap interface itself. Routing table entries are
automatically deleted when the interface is, but iptables/ebtables
rules are not. (Although it would be a nice little kernel addition if
they could be flagged to be.)
But now, thinking a bit more clearly... why is the helper separate
from "-net script="?
Overall, I envisage this happening (sorry for making up the name
tap-up-helper, as I seem to have lost your patch mails):
tap-up-helper= # Sets up tap interface, adds to bridge if needed.
script= # Sets up IP config
....QEMU runs....
downscript= # Removes IP config
tap-down-helper= # If only for symmetry!
We does tap-up-helper need to be separate from script? Does QEMU need
to do something in between calling the two?
If not, then the existing "-net script=" script could just send the
tap descriptor as well as anything else it does, couldn't it?
-- Jamie
