Re: Question about Xen reboot on panic

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 11/11/2015 23:21, Meng Xu wrote:
>
>> Finally, I can't tell from your paste below, but ensure that you are
>> always using a debug hypervisor.
> The source file Config.mk under the xen folder has
> debug ?= y
>
> In addition,  "xl dmesg |grep debug" gives me:
>
> (XEN) Xen version 4.6-unstable (root@) (gcc (Ubuntu/Linaro
> 4.6.3-1ubuntu5) 4.6.3) debug=y Wed Nov 11 17:06:30 EST 2015
>
> So I guess I'm using the debug hypervisor.

You are

>
> I reboot the system after removing all of those useless options (that
> is, no more "reboot=k panic=2 panic_on_oops=1" in the Xen boot command
> line.)
>
> Is there anything else I can do to force Xen always reboot at panic or oops?

Unless you specify noreboot, Xen will try its hardest to reboot the
system.  It is possible that you have a dodgy firmware which interacts
poorly with the default methods.

Does normal reboot from dom0 work as intended?

If not, debug in the following order:

* `reboot` from the dom0 shell
* `echo b > /proc/sysrq-trigger` from the dom0 shell
* `xl debug-keys R` from the dom0 shell
* CTRL-A x3, R from the serial console

Those are the reboot options.  It is also possible that a kexec kernel
is being loaded and that is getting stuck.

The crash options are:
* `kexec -p`
* `echo c > /proc/sysrq-trigger`
* `xl debug-keys C`

If those don't work then you will need to start instrumenting Xen to
work out where stuff is going wrong.

~Andrew