Re: [Xen-devel] domU hang in xenbus_scanf for /control/platform-feature-xs_reset_watches

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Aug 22, 2014 at 07:15:58PM +0530, manish jaggi wrote:
> On 21 August 2014 22:53, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> > On Thu, 2014-08-21 at 12:54 +0100, Wei Liu wrote:
> >> On Wed, Aug 20, 2014 at 06:54:26PM +0530, manish jaggi wrote:
> >> > In xenstore-ls I dont see this node (control node is not there as well)
> >> > What could be missing here.
> >> >
> >>
> >> It's libxl's resposibility to write that node. However libxl should fail
> >> if it fails to create that node. See libxl_create.c.
> >>
> >
> > But also the guest ought to be robust to that node not being present,
> > afterall that is the point of a feature-* node...
> >
> > Ian.
> >
> >> You can try to increase xl's verbosity to have an idea what went wrong.
> >>
> >> Wei.
> >>
> >> > _______________________________________________
> >> > Xen-devel mailing list
> >> > Xen-devel@xxxxxxxxxxxxx
> >> > http://lists.xen.org/xen-devel
> >>
> >> _______________________________________________
> >> Xen-devel mailing list
> >> Xen-devel@xxxxxxxxxxxxx
> >> http://lists.xen.org/xen-devel
> >
> >
> I debugged a bit more to put xen_raw_printk in xs_talkv, xb_write and
> notify_remote_via_evtchn. I found that the notify_remote_via_evtchn
> for port 1 did not complete domU didnt return from that function. (I
> added two printk before and after the HYPERVISOR_event_channel_op).
> 

How odd. notify_remote_via_evtchn only issues one hypercall and does
nothing else. So you're saying it's stuck in hypervisor? Setting up a
series console and get hypervisor log might help.

> __func__, __LINE__
> 
> (d1) xs_talkv 249
> (d1) xb_write 104
> (d1) xb_write 137
> (d1) notify_remote_via_evtchn 62 PORT=1
> notify_remote_via_evtchn 62 PORT=5
> notify_remote_via_evtchn 64 PORT=5
> notify_remote_via_evtchn 62 PORT=5
> notify_remote_via_evtchn 64 PORT=5
> 
> Dumping event channel on Xen Console gave this
> 
> (XEN) 'e' pressed -> dumping event-channel info
> (XEN) Event channel information for domain 0:
> (XEN) Polling vCPUs: {}
> (XEN)     port [p/m/s]
> (XEN)        1 [0/0/0]: s=3 n=0 x=0 d=0 p=3
> (XEN)        2 [0/0/0]: s=5 n=0 x=0 v=2
> (XEN)        3 [0/0/0]: s=3 n=0 x=0 d=0 p=1
> (XEN)        4 [0/0/0]: s=5 n=0 x=0 v=3
> (XEN)        5 [0/0/0]: s=3 n=0 x=0 d=1 p=1
> (XEN)        6 [0/0/0]: s=3 n=0 x=0 d=1 p=2
> (XEN) Event channel information for domain 1:
> (XEN) Polling vCPUs: {}
> (XEN)     port [p/m/s]
> (XEN)        1 [1/0/  -   ]: s=3 n=0 x=0 d=0 p=5
> (XEN)        2 [0/1/  -   ]: s=3 n=0 x=0 d=0 p=6
> 
> What does p/m/s/x/n/d mean ? Any pointers on where I should start looking ?

Look at Xen source code common/event_channel.c.

Wei.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel