Re: [Qemu-discuss] [BUG or NOT] NICs in up state can not receive any packages if other one NIC is in down state

[Stefan Hajnoczi]

On Fri, Aug 17, 2012 at 09:38:45AM +0800, Rongqing Li wrote:
> 
> 
> On 2012年08月16日 20:57, Stefan Hajnoczi wrote:
> >I think the solution is not to drop Vincent/Zhi Yong's code.  Instead we
> >should distinguish between "up" and "down".  If a net client is "up" but
> >cannot receive, then the hub will queue the packet.  If a net client is
> >"down" then the hub will ignore the client and send packets to other
> >clients.
> >
> >I don't have patches for this but have added it to my TODO list.
> >
> >Stefan
> 
> Ok, Thanks for you explanation! and expect your patch.

If you have time to fix this I suggest you try to submit the patch
because I may not get to within the next week.

We need a way to determine whether the interface is up/down.  There is
already a link_down flag that can be set.  Not sure if its semantics are
exactly what we need, you'd need to check net.h/net.c.

The second step is looking at qemu_can_send_packet() and .can_receive().
net/hub.c:net_hub_port_can_receive() needs to be tweaked so peers with
link_down are skipped.

Stefan