Does Xen actually work ?

**WitchCraft** · June 20th, 2012

Can anybody answer my two questions here:

http://askubuntu.com/questions/15386...-my-xen-config

and

http://askubuntu.com/questions/15386...idging-trouble

**CharlesA** · June 20th, 2012

Both are dead links.

Take a look here:
https://help.ubuntu.com/community/Xen

**WitchCraft** · June 21st, 2012

Right, I just managed to solve these, after hours of trying.
So I deleted them.

The only remaining problem is that it doesn't work with a WIFI interface.

I have exactly the same configuration on my server and my laptop.
On the server, I add this to /etc/network/interfaces

Code:

auto xenbr0
iface xenbr0 inet dhcp
        bridge_ports eth0

On my laptop, I need to take wlan0 instead of eth0:

Code:

auto xenbr0
iface xenbr0 inet dhcp
        bridge_ports wlan0

On the server it works, on the laptop I get:
operation not supported.

Apparently because the wifi-card cannot be set into master mode.
However, I really doubt that, as iw lists AP (access point) as a supported mode. This is probably some bogus bug with the new MAC80211 driver.

Right now I'm exprimenting with hostapd, as this tool must set the network card into master mode

Code:

hostapd -d -B /etc/hostapd/hostapd.conf

However, something is very wrong...

**CharlesA** · June 21st, 2012

I've not tried to bridge wireless before.

Did you see this?
http://virt.kernelnewbies.org/XenWifiNetwork

**WitchCraft** · June 21st, 2012

Originally Posted by CharlesA

I've not tried to bridge wireless before.

Did you see this?
http://virt.kernelnewbies.org/XenWifiNetwork

Is this supposed to be a joke ?
It's untested and looking at it, I have
a) seen that the author was unable to install xen
b) seen that he's using NAT instead of bridging (which already works without this)
c) seen that he's working with eth0 and eth1 and not wlan0
d) no idea what the idea behind this is
e) no clue as to why this should work

**CharlesA** · June 21st, 2012

Originally Posted by WitchCraft

Is this supposed to be a joke ?

Apparently. It was the second hit on Google.

First hit is here:
http://wiki.xen.org/wiki/Main_Page

As for master mode, read here:
https://help.ubuntu.com/community/WifiDocs/MasterMode

**WitchCraft** · June 23rd, 2012

Originally Posted by CharlesA

Apparently. It was the second hit on Google.

First hit is here:
http://wiki.xen.org/wiki/Main_Page

As for master mode, read here:
https://help.ubuntu.com/community/WifiDocs/MasterMode

Apparently, you seem to be under the impression that I didn't Google my problem before I posted here.

I assure you this is not the case.
I already read those unfortunately rather useless pages a while ago (well I admit, not everything of course, as I don't have a few decades to spare).

Unfortunately, the problem is a bit long to describe.
I posted an entire Xen howto in the tutorials section, but it will take a little time until it is approved.

Bottom line is:
The real problem is, that apparently Linux-Kernel >= 2.6.33 won't let you bridge a wireless interface in managed mode at all unless you enable 4addr.

But the version of iw in the Ubuntu 11.10 repositories (0.9x) is so outdated (4 years old), that it doesn't even recognize the command

Code:

iw dev wlan0 set 4addr on

One first needs to download version 3.4 from

Code:

http://linuxwireless.org/download/iw/

then compile and install it until one can do that.

Afterwards, the entire network breaks down (bug in network-manager or in the Linux kernel?)

I haven't been able to get this working, although

Code:

brctl addif br0 wlan0

now works with 4addr on

and

Code:

brctl show

now shows xenbr0 as bridged to wlan0.

Just that now there is no internet connection on wlan0.
(ip address shows fine).

BTW, as completely unrelated rant, with the new xen-kernel, my laptop now crashes every time when it should come-back from stand-by. With the normal kernel, this worked fine.