[Xen-users] tap:aio not working. Read_msg failure - CTLMSG_PID(0), Unable to contact disk process

[Wiebe Cazemier <halfgaar@xxxxxxx>]

Hi,

I'm trying to boot a virtual machine with the 'tap:aio:' driver as opposed
to 'file:'. However, I'm running into a problem.

I have two freshly installed Debian Lenny x86 machines, which both exhibit the
same problem. My Xen is 3.2-1-i386. Kernel is 2.6.26-2-xen-686.

When I try to start the virtual machine, it hangs when it wants to mount root,
and it starts counting down:

[    6.349878] XENBUS: Waiting for devices to initialise: 295s...

After Googling, I found out it was because the blktapctrl process wasn't
running. This was because the module xenblktap wasn't loaded by xend. I had to
include that in /etc/modules to autoload it (which is odd enough in and of
itself; it should to that automatically).

Anyway, after restating xend the blktapctrl process runs:

2410 ?        Ssl    0:00 /usr/lib/xen-3.2-1/bin/blktapctrl

There is improvement, but it still doesn't work. It keeps repeating:

Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Read_msg failure - CTLMSG_PID(0)
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Unable to contact disk process
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Unmapping vbd
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Write_msg called: CTLMSG_CLOSE
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: DEL_DISKTYPE: Freeing entry
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Received a poll for a new vbd
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: /dev/xen/blktap1 device already exists
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Received device id 1 and major 249,
sent domid 9 and be_id 2049
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Detected handle: [aio]
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Process does not exist:
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Launching process, CMDLINE
[tapdisk /var/run/tap/tapctrlwrite1 /var/run/tap/tapctrlread1]
Mar 26 13:29:53 node00 BLKTAPCTRL[2407]: Write_msg called: CTLMSG_PID

I thought maybe it's because tapdisk isn't in the path. It's only
in /usr/lib/xen-3.2-1/bin/. But, symlinking it in /usr/local/bin doesn't help.
One thing is fore sure, the tapdisk executable isn't called, it's atime does
not change when I start the VM.

Does anybody have an idea?


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