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Re: vifs not working?

Sarton O'Brien wrote:
On Fri, 23 May 2008 09:42:50 am der Mouse wrote:
Error: Device 0 (vif) could not be connected. Hotplug scripts not
This despite specifying "script=/usr/bin/true" on the network-attach
command line.
I think your "script" is too simplistic. :)
Apparently so.  That was based on the vif-bridge script in the xen
howto, which does ifconfig and brconfig commands but none of the
xenstore-* stuff.

I guess you'll need tot do at least something like the xenstore-write
line in the vif-ip script that comes with the xentools pkg.
This turns out to be correct.  The script named in the script= line on
the xm network-attach command is run with arguments
/local/domain/0/backend/vif/8/1 and 4.  The script that comes with the
xentools stuff does nothing in this case; it expects 6 or 2 as the
second argument.  (Of course, the semantics of this magic number are
completely undocumented.)  But running

dom0# xenstore-write /local/domain/0/backend/vif/8/1/hotplug-status
manually makes the xm network-attach command exit, and the xennet and
vif interfaces now stick around.

So that the scripts that come with the package don't even work as-is,
and can't work without divining undocumented values pased by an
undocumented but critical program, and requires the running of another
undocumented program to get basic functionality working.  I'm...well,
I'm pretty impressed by xen to begin with, but quite disappointed in
the package and related stuff.

That's cool that you got it going, it would have easily been a few wasted hours for me to poke around. Unfortunately there are only a couple of people working on xen so the functionality has progressed slowly in certain areas.

(I've been using the 2008Q1 packages, on the theory that that's the closest approximation to in sync with
4.0; do newer xen packages (a) work with 4.0 and (b) fix things?)

There's an incompatibility between the latest xentools and the 4.0 release kernels. So it's current or release but nothing in between :( ... well reliably anyway.

On a -current dom0 kernel:

The main problem is that xenbackendd isn't invoked at all, therefore the scripts never run.
xenbackendd listens for XS_WATCH_EVENT, but those never come.

In xen/xenbus/xenbus_xs.c:process_msg  I see two type of events:
XS_READ and XS_ERROR for a block device (vbd).


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