Re: [Xen-devel] [patch] xen udev rule interfering with openvpn

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-05-23 at 03:22 +0100, Teck Choon Giam wrote:

> >
> > I think the reason this effects xm and not xl is that libxl uses
> > script=none to disable qemu-ifup while xend does not and instead ends up
> > using qemu-ifup which does some fiddling with the device too, including
> > bringing it up.
> 
> Ok, so default for xend is using script=qemu-ifup if script is not
> set?  Am I right about this?

Yes.

> > The proper fix is probably to change xend, I'm a bit wary of this,
> > especially for a 4.1 backport, but the following looks right and works
> > for me. It's a bit more complex since in libxl we seem to only do this
> > for Linux (i.e. not NetBSD) and I guess we should do the same in xend
> > too.
> 
> Err... if we are going to change default behaviour will we be
> affecting those users who is upgrading from xen-4.1 to xen-4.2?

This was already a deliberate change made in xl, it does not effect the
guest config, only the mechanisms by which that configuration is
achieved. I think extending this to xend in order not to break xend in
4.2 is worthwhile.

I don't think we should be backporting any of this to 4.1 though.

> If your fix patch is going into xen-unstable for sure, I will re-run
> my tests by then.  I hope it doesn't affect current domUs
> configuration (I mean we shouldn't need to change domU configuration)
> especially when users prefer to use xm then xl in xen-4.2.

There should be no guest config change necessary.

Ian.

> 
> Thanks.
> 
> Kindest regards,
> Giam Teck Choon
> 
> 
> >
> > Ian
> >
> > # HG changeset patch
> > # User Ian Campbell <ian.campbell@xxxxxxxxxx>
> > # Date 1337692747 -3600
> > # Node ID 426bbf58cea4559464b6e5d3ff0f65324a5f5926
> > # Parent  72ca5bc4eb6b91fa8dff51d439bd05f5586179df
> > xend: do not run a hotplug script from qemu on Linux
> >
> > The current vif-hotplug-common.sh for renaming the tap device is failing
> > because it is racing with this script and therefore the device is 
> > unexpectedly
> > up when we come to rename it.
> >
> > Fix this in the same way as libxl does, by disabling the script (only on
> > Linux).
> >
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> >
> > diff -r 72ca5bc4eb6b -r 426bbf58cea4 tools/python/xen/xend/image.py
> > --- a/tools/python/xen/xend/image.py    Tue May 22 11:29:50 2012 +0100
> > +++ b/tools/python/xen/xend/image.py    Tue May 22 14:19:07 2012 +0100
> > @@ -919,8 +919,13 @@ class HVMImageHandler(ImageHandler):
> >                        (nics, mac, model))
> >             vifname = "vif%d.%d-emu" % (self.vm.getDomid(), nics-1)
> >             ret.append("-net")
> > -            ret.append("tap,vlan=%d,ifname=%s,bridge=%s" %
> > -                       (nics, vifname, bridge))
> > +            if osdep.tapif_script is not None:
> > +                script=",script=%s,downscript=%s" % \
> > +                        (osdep.tapif_script, osdep.tapif_script)
> > +            else:
> > +                script=""
> > +            ret.append("tap,vlan=%d,ifname=%s,bridge=%s%s" %
> > +                       (nics, vifname, bridge, script))
> >
> >         if nics == 0:
> >             ret.append("-net")
> > diff -r 72ca5bc4eb6b -r 426bbf58cea4 tools/python/xen/xend/osdep.py
> > --- a/tools/python/xen/xend/osdep.py    Tue May 22 11:29:50 2012 +0100
> > +++ b/tools/python/xen/xend/osdep.py    Tue May 22 14:19:07 2012 +0100
> > @@ -30,6 +30,10 @@ _vif_script = {
> >     "SunOS": "vif-vnic"
> >  }
> >
> > +_tapif_script = {
> > +    "Linux": "no",
> > +}
> > +
> >  PROC_XEN_BALLOON = '/proc/xen/balloon'
> >  SYSFS_XEN_MEMORY = '/sys/devices/system/xen_memory/xen_memory0'
> >
> > @@ -257,6 +261,7 @@ def _get(var, default=None):
> >
> >  xend_autorestart = _get(_xend_autorestart)
> >  vif_script = _get(_vif_script, "vif-bridge")
> > +tapif_script = _get(_tapif_script)
> >  lookup_balloon_stat = _get(_balloon_stat, _linux_balloon_stat)
> >  get_cpuinfo = _get(_get_cpuinfo, _linux_get_cpuinfo)
> >  prefork = _get(_get_prefork, _default_prefork)
> >
> >



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