Re: [Patch] kexec: remove KMSG_DUMP_KEXEC (was Re: Query about kdump_msg hook into crash_kexec())

KOSAKI Motohiro
2011-05-30T05:13:45Z

(2011/05/27 5:10), Andrew Morton wrote:
> On Thu, 3 Feb 2011 13:53:01 +0900 (JST)
> KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
>
>>>> I wrote why this is no good idea by another mail. Please see it.
>>>> Anyway you have a right to don't use this feature.
>>>>
>>>
>>> But you have not explained that why do you need to hook into crash_kexec()
>>> and you have also not explained why do you need to send out kdump_msg()
>>> notification if kdump is configured.
>>>
>>> Some detailed explanation here would help.
>>
>> Hi,
>>
>> I send it you now :)
>>
>
> What happened with this? kexec-remove-kmsg_dump_kexec.patch has two acks
> and one unexplained nack :(

http://groups.google.com/group/linux.kernel/browse_thread/thread/1084f406573d76ac/ee19e34b45f83536?lnk=raot&pli=1

At last mail, Vivek proposed move kms_dump() instead remove. and I asked following question and
I've got no response. I'm still waiting his.

> I'm sorry I've missed this mail long time.
>
>> > ---------------------------------------------------------------------
>> > @@ -74,6 +75,7 @@ NORET_TYPE void panic(const char * fmt, ...)
>> > dump_stack();
>> > #endif
>> > + kmsg_dump(KMSG_DUMP_PANIC);
>> > /*
>> > * If we have crashed and we have a crash kernel loaded let it handle
>> > * everything else.
>> > * Do we want to call this before we try to display a message?
>> > */
>> > crash_kexec(NULL);
>> > ---------------------------------------------------------------------
>> And I think to compensate for that somebody introduced additional
>> kmsg_dump(KEXEC) call inside crash_kexec() and put it under CONFIG
>> option so that one can change the behavior based on config options.
>> I think this makes the logic somewhat twisted and an unnecessary call
>> inside crash_kexec(). So until and unless there is a strong reason we
>> can get rid of KEXEC event and move kmsg_dump call before crash_kexec()
>> for now and see how does it go, IMHO.
>
>
> I think I can agree your proposal. But could you please explain why do
> you think kmsg _before_ kdump and kmsg _in_ kdump are so different?
> I think it is only C level difference. CPU don't care C function and
> anyway the kernel call kmsg_dump() because invoke second kernel even
> if you proposal applied.
> It is only curious. I'm not against your proposal.
> Thanks.