Re: Query about kdump_msg hook into crash_kexec()

Américo Wang
2011-02-01T07:39:05Z

On Mon, Jan 31, 2011 at 11:33:15PM -0800, Eric W. Biederman wrote:
>Américo Wang <xiyou.wangcong@gmail.com> writes:
>
>> On Mon, Jan 31, 2011 at 05:59:39PM -0500, Vivek Goyal wrote:
>>>
>>>Anyway, if an image is loaded and we have setup to capture dump also
>>>why do we need to save kmsg with the help of an helper. I am assuming
>>>this is more of a debugging aid if we have no other way to capture the
>>>kernel log buffer. So if somebody has setup kdump to capture the
>>>vmcore, why to call another handler which tries to save part of the
>>>vmcore (kmsg) separately.
>>>
>>
>> Well, kmsg dumper is not only for panic/oops, it can also save kernel
>> messages when the system is reboot/halt.
>>
>> Yeah, it is true that vmcore contains log_buf, but I think the users
>> of ramoops/mtdoops are mainly those who don't have kdump configured
>> in their kernels, they are cheaper than kdump, but less powerful
>
>The issue is the inane call inside crash_kexec.
>
>It requires both a kexec kernel to be loaded and it requires you to be
>crashing. Given that when I audited the kmsg_dump handlers they really
>weren't safe in a crash dump scenario we should just remove it.
>

Probably, I think we need to get rid of KMSG_DUMP_KEXEC.