Re: [Qemu-devel] [Bug 1326986] [NEW] e1000 - no link detected by

["Gabriel L. Somlo" <gsomlo@gmail.com>]

On Thu, Jun 05, 2014 at 10:55:39PM -0400, Matthew Gamble wrote:
> Gabriel,
> 
> I tried your suggestion and while the OS doesn't detect a link, it does
> send the following right after toggling the link:
> 
> e1000: set_ics 4, ICR 4, IMR 0
> 
> e1000: set_ics 4, ICR 4, IMR 0
> 
> Without diving into the intel programming guide myself does that help in
> any way?  Perhaps it's expecting an interrupt to fire that isn't?

Not right away :) I'm currently debugging a similar issue where OS X
guests do not see link with e1000, but bouncing the link from the
host side (via the qemu monitor) causes the link to come up and work fine.

I think currently qemu's e1000 link negotiation is a bit flaky, but since
windows and linux can work around it, we're the first ones to notice...

There's still a good likelihood that whatever fixes your issue might also
help with mine (and vice versa), but I won't get a chance to dig deeper
until next week (and I'm also not all that familiar with the deep voodoo
of link negotiation, so it might take a while if it's down to me... :)

Cheers,
--Gabriel

> On Thu, Jun 5, 2014 at 10:44 PM, Gabriel L. Somlo <gsomlo@gmail.com> wrote:
> 
> > Matthew Gamble <mgamble@mgamble.ca> wrote:
> > > I'm trying to get a VXWorks image running inside a qemu guest.  I have
> > > the machine running, however, the vxworks image only has support for the
> > > 82544EI device so I had to change the device ID in e1000.c to get the
> > > device even recognized so I'm not sure if this is a bug or an issue for
> > > the development list.
> > >
> > > After changing e1000.c, the device is now seen by the guest OS, however,
> > it never gets a link.  I've attached the e1000 debug logs in the hopes that
> > someone can help me understand where to start looking into why this guest
> > won't get a link.
> > >
> > > I tested the updated e1000 driver with a debian live CD and the card
> > > works under it, so it doesn't appear that the issue is with the driver
> > > string change but rather something in the e1000 driver itself.
> > >
> > > Here is the command I'm using to start QEMU:
> > >
> > > /opt/qemu/bin/qemu-system-i386  -cpu coreduo -hda /root/vxworks_test -m
> > > 2048 -netdev tap,ifname=tap0,id=net0 -netdev tap,ifname=tap1,id=net1
> > > -device e1000,netdev=net0,mac=00:00:e8:01:02:03 -device
> > > e1000,netdev=net1,mac=00:00:e8:01:02:04 -boot c -curses -no-kvm -D
> > > /tmp/qemu.log 2>/tmp/e1000.log
> >
> > Can you try this:
> >
> > Add "-monitor stdio" to your qemu command line, and give an id to at
> > least one of your e1000 devices, like so:
> >
> > "-device e1000,netdev=net0,mac=00:00:e8:01:02:03,id=eth0"
> >
> > Then after the guest is finished booting (with no link on the e1000
> > interfaces), from the qemu monitor prompt issue these two commands:
> >
> > set_link eth0 off
> > set_link eth0 on
> >
> > I'd be curious to find out if this causes the guest to see a link
> > become available...
> >
> > Thanks,
> > --Gabriel
> >

-- 
------------------------------------
Gabriel L. Somlo
Director of Computing Services
Information Networking Institute
Carnegie Mellon University
4616 Henry St., Pittsburgh, PA 15213
+1.412.268.9310      www.ini.cmu.edu