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

[manish jaggi <manishjaggi.oss@xxxxxxxxx>]

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
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>> 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).

__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 ?

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