Xen devel - Sep 2012 - [PATCH] kexec/noreboot: Don't kexec_crash() if noreboot has been requested.

This issue came up when debugging pcpu linked list corruption (patches
for that issue to follow).

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com



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>>> On 07.09.12 at 15:05, Andrew Cooper
<andrew.cooper3@citrix.com> wrote:
> This issue came up when debugging pcpu linked list corruption (patches
> for that issue to follow).
Hmm, that''s a matter of taste of course. Nor is running kdump
really a (direct) reboot action. Both ways have their reasoning
imo, so I''m not sure whether keeping things as is or applying the
patch is the better thing.

Jan

On 07/09/12 14:16, Jan Beulich wrote:
>>>> On 07.09.12 at 15:05, Andrew Cooper
<andrew.cooper3@citrix.com> wrote:
>> This issue came up when debugging pcpu linked list corruption (patches
>> for that issue to follow).
> Hmm, that''s a matter of taste of course. Nor is running kdump
> really a (direct) reboot action. Both ways have their reasoning
> imo, so I''m not sure whether keeping things as is or applying the
> patch is the better thing.
>
> Jan
Hmm yes - I guess its not as clean cut as I thought, but I would still
argue that this patch is the lest surprising alternative.

One tweak I am thinking of working on soon is a "pause-on-reboot"
feature which is a bit like noreboot, but will accept a passphrase and
continue with the reboot, so you can ''pause'', see the dying
panic then
reboot without needing to invoke the server power management.

(This may have been as a result of being given details for the wrong
server power management interface IP address when debugging a server in
a data center 7 time zones away, and getting rather confused when it
didn''t make any attempt to reboot.  I imagine someone else might get
equally irate if their server was rebooting without warning.)

~Andrew
>
>
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-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com

On 07/09/2012 14:16, "Jan Beulich" <JBeulich@suse.com> wrote:
>>>> On 07.09.12 at 15:05, Andrew Cooper
<andrew.cooper3@citrix.com> wrote:
>> This issue came up when debugging pcpu linked list corruption (patches
>> for that issue to follow).
> 
> Hmm, that''s a matter of taste of course. Nor is running kdump
> really a (direct) reboot action. Both ways have their reasoning
> imo, so I''m not sure whether keeping things as is or applying the
> patch is the better thing.
I note though that kexec_crash() should be stubbed out in the header file
when !CONFIG_KEXEC, rather than ifdef at the caller. By the by.

 -- Keir
> Jan
>

On 07/09/12 16:03, Keir Fraser wrote:
> On 07/09/2012 14:16, "Jan Beulich" <JBeulich@suse.com>
wrote:
>
>>>>> On 07.09.12 at 15:05, Andrew Cooper
<andrew.cooper3@citrix.com> wrote:
>>> This issue came up when debugging pcpu linked list corruption
(patches
>>> for that issue to follow).
>> Hmm, that''s a matter of taste of course. Nor is running kdump
>> really a (direct) reboot action. Both ways have their reasoning
>> imo, so I''m not sure whether keeping things as is or applying
the
>> patch is the better thing.
> I note though that kexec_crash() should be stubbed out in the header file
> when !CONFIG_KEXEC, rather than ifdef at the caller. By the by.
>
>  -- Keir
Agreed - I will put it on my todo list to fix.  (I think its elsewhere
in the codebase as well)

~Andrew
>
>> Jan
>>
>
-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com