Custom vif setup script not working with mirage-net-xen 1.4.1

[MagnusS]

For jitsu we use a faster vif setup script (available here and in C here) instead of the default in /etc/xen/scripts/vif-bridge. With mirage-net-xen version 1.4.1 they stopped working. Downgrading to 1.4.0 fixes the problem.

The unikernel hangs after "MAC: ..." :

Netif: add resume hook
Netif.connect 0
Netfront.create: id=0 domid=0
MAC: 00:16:3e:00:9f:c4

This is in xenstore:

 vif = ""
  0 = ""
   backend = "/local/domain/0/backend/vif/2/0"
   backend-id = "0"
   state = "4"
   handle = "0"
   mac = "00:16:3e:00:9f:c4"
   tx-ring-ref = "9"
   rx-ring-ref = "8"
   event-channel = "4"
   request-rx-copy = "1"
   feature-rx-notify = "1"
   feature-sg = "1"

As the default script works I guess the problem is in the custom scripts, but I'm not sure what should be added to them to fix it. Any suggestions? /cc @djs55

[djs55]

The only change in 1.4.1 was to wait for the backend to enter state=4. I'd
be interested to know what was in the xenstore backend directory
(/local/domain/0/backend/vif/2/0 in this case). There might be a log
message from netback in the domain 0 log.

The standard vif script might be doing a bit more than ours? In the past it
would write a special 'hotplug-status=connected' key, I'm not sure if
that's still needed.

Do you know if libxl is running the script itself or via udev? IIRC it's a
configuration option which is written somewhere in xenstore. Perhaps the
hotplug-status=connected key was only needed for the running via udev case.

(sorry for the brain dump)

On Fri, May 1, 2015 at 3:42 PM, Magnus Skjegstad notifications@github.com
wrote:

For jitsu we use a faster vif setup script (available here
https://github.com/mirage/jitsu/blob/master/scripts/fast-vif-bridge and
in C here https://github.com/mirage/jitsu/blob/master/scripts/add_vif.c)
instead of the default in /etc/xen/scripts/vif-bridge. With mirage-net-xen
version 1.4.1 they stopped working. Downgrading to 1.4.0 fixes the problem.

The unikernel hangs after "MAC: ..." :

Netif: add resume hook
Netif.connect 0
Netfront.create: id=0 domid=0
MAC: 00:16:3e:00:9f:c4

This is in xenstore:

vif = ""
0 = ""
backend = "/local/domain/0/backend/vif/2/0"
backend-id = "0"
state = "4"
handle = "0"
mac = "00:16:3e:00:9f:c4"
tx-ring-ref = "9"
rx-ring-ref = "8"
event-channel = "4"
request-rx-copy = "1"
feature-rx-notify = "1"
feature-sg = "1"

As the default script works I guess the problem is in the custom scripts,
but I'm not sure what should be added to them to fix it. Any suggestions?
/cc @djs55 https://github.com/djs55

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#14.

Dave Scott

[MagnusS]

Thanks! Writing hotplug-status=connected to xenstore seems to fix the problem with fast-vif-bridge at least.

/local/domain/0/libxl/disable_udev is set to "1" in Xenstore

[MagnusS]

Hm looks like it didn't fix the problem completely... maybe I was just lucky and won the race a few times.