Re: [Xen-users] 2.6.18.8 xen.org dom0 kernel w/RHEL 5 PV on HVM guests

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Mar 22, 2010 at 11:13:43AM -0700, Andrew Evans wrote:
> On 03/18/10 15:32, Pasi Kärkkäinen wrote:
> > Hmm.. can you try with the RHEL5 default hypervisor (3.1.2) ?
> > (and the 2.6.18-xen dom0 kernel) 
> >
> > Would be good to know if it makes any difference.
> >   
> 
> I installed the xen-3.0.3 RPM (xm dmesg/xm info says 3.1.2 -- what the
> heck is up with Red Hat's version numbering?)
>

Xen hypervisor in RHEL5 comes in the kernel rpm together with the dom0 kernel.

RHEL5 currently has Xen 3.1.2 (+patches) hypervisor, but the userland
tools (xen rpm) are based on 3.0.3. 

That is because RHEL5 is an enterprise distro, and they need to keep
the ABI stable.. RHEL 5.0 first shipped with Xen 3.0.3 so they cannot
change versions and break things just like that. 


> but am getting the dreaded
> "Hotplug scripts not working" errors. Looks like a TUN/TAP problem:
> 
> $ cat qemu-dm.4910.log
> domid: 2
> qemu: the number of cpus is 7
> Change xvda to look like hda
> Change xvdb to look like hdb
> Change xvdc to look like hdc
> Watching /local/domain/2/logdirty/next-active
> Watching /local/domain/0/device-model/2/command
> /etc/xen/qemu-ifup: could not launch network script
> Could not initialize device 'tap'
> 
> $ cat xend-debug.log.1
> Xend started at Thu Mar 18 23:25:38 2010.
> Nothing to flush.
> Nothing to flush.
> can't add tap0 to bridge eth0: Operation not supported
> can't add tap0 to bridge eth0: Operation not supported
> 
> $ cat /etc/xen/qemu-ifup
> #!/bin/sh
> 
> #. /etc/rc.d/init.d/functions
> #ulimit -c unlimited
> 
> echo 'config qemu network with xen bridge for ' $*
> 
> ifconfig $1 0.0.0.0 up
> brctl addif $2 $1
> 
> strace of `brctl addif eth0 tap0` shows:
> 
> ioctl(4, 0x89a2, 0x7fff724c1e50)        = -1 EOPNOTSUPP (Operation not
> supported)
> ioctl(4, SIOCDEVPRIVATE, 0x7fff724c1e50) = -1 EOPNOTSUPP (Operation not
> supported)
> write(2, "can't add tap0 to bridge eth0: O"..., 55can't add tap0 to
> bridge eth0: Operation not supported
> ) = 55
> exit_group(1)                           = ?
> 
> I think the RHEL 5 2.6.18 dom0 kernel must support this ioctl, while the
> xen.org 2.6.18.8 dom0 kernel must not. So RHEL 5's Xen 3.1.2 package on
> xen.org 2.6.18.8 dom0 kernel looks like a dead end.
> 
> I'll go back to Xen 3.4.2 with xen.org 2.6.18.8 dom0. PV disk on HVM is
> actually not very important to me at the moment.
> 

Do you have a bridge called 'eth0' for real? Try "brctl show" to verify.
RHEL5 as a default creates 'xenbr0', not 'eth0'.

-- Pasi


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