xen discuss - Sep 2008 - How to enter the kmdb mode in a hvm solaris domu when it hang?

Hi,
The Dom0 is snv_97 ,the Domu is a HVM s10_u5.
I booted the domu which loaded the mdb module.

-bash-3.00# modinfo |grep mdb
3 fffffffffbaa10a0 a04f0 - 0 kmdbmod ()
176 fffffffff406a9f8 748 171 1 kmdb (kmdb driver 1.3)

If the Domu hang(can''t run he command line "mdb -K" by
shell),
how can I enter the kmdb module to debug the deadlock issue?

Thanks,
Colin

On Thu, Sep 04, 2008 at 06:40:51PM +0800, Colin Yi wrote:
> The Dom0 is snv_97 ,the Domu is a HVM s10_u5.
> I booted the domu which loaded the mdb module.
> 
> -bash-3.00# modinfo |grep mdb
> 3 fffffffffbaa10a0 a04f0 - 0 kmdbmod ()
> 176 fffffffff406a9f8 748 171 1 kmdb (kmdb driver 1.3)
> 
> If the Domu hang(can''t run he command line "mdb -K" by
shell),
> how can I enter the kmdb module to debug the deadlock issue?
There isn''t any way AFAIK (the serial console trick doesn''t
work, I
believe). Of course you can still use the deadman timer if that''s able
to run.

regards
john

John Levon wrote:
> On Thu, Sep 04, 2008 at 06:40:51PM +0800, Colin Yi wrote:
> 
>> The Dom0 is snv_97 ,the Domu is a HVM s10_u5.
>> I booted the domu which loaded the mdb module.
>>
>> -bash-3.00# modinfo |grep mdb
>> 3 fffffffffbaa10a0 a04f0 - 0 kmdbmod ()
>> 176 fffffffff406a9f8 748 171 1 kmdb (kmdb driver 1.3)
>>
>> If the Domu hang(can''t run he command line "mdb -K"
by shell),
>> how can I enter the kmdb module to debug the deadlock issue?
> 
> There isn''t any way AFAIK (the serial console trick
doesn''t work, I
> believe). Of course you can still use the deadman timer if that''s
able
> to run.
Is it possible to get Xen to fake up an NMI?

I have a very vague recollection there''s some magic setting you can 
apply somewhere (probably in the pcplusmp module) which gets kmdb to 
spring up if an NMI is received.

-- 
Andrew

On Thu, Sep 04, 2008 at 01:45:57PM +0100, Andrew Gabriel wrote:
> >There isn''t any way AFAIK (the serial console trick
doesn''t work, I
> >believe). Of course you can still use the deadman timer if
that''s able
> >to run.
> 
> Is it possible to get Xen to fake up an NMI?
Yes, but not in the version we ship. There''s "xm sysrq" but
no support
for that in HVM.
> I have a very vague recollection there''s some magic setting you
can
> apply somewhere (probably in the pcplusmp module) which gets kmdb to 
> spring up if an NMI is received.
Yep, there is.

regards
john