Re: [Fastboot] [RFC][PATCH] Add missing notifier before crashing

["Akiyama, Nobuyuki" <akiyama.nobuyuk@jp.fujitsu.com>]

On Fri, 02 Jun 2006 05:52:32 -0600
ebiederm@xmission.com (Eric W. Biederman) wrote:

> Preben Traerup <Preben.Trarup@ericsson.com> writes:
> 
> > Since I'm one of the people who very much would like best of both worlds,
> > I do belive Vivek Goyal's concern about the reliability of kdump must be
> > adressed properly.
> >
> > I do belive the crash notifier should at least be a list of its own.
> >   Attaching element to the list proves your are kdump aware - in theory
> >
> > However:
> >
> > Conceptually I do not like the princip of implementing crash notifier
> > as a list simply because for all (our) practical usage there will only
> > be one element attached to the list anyway.
> >
> > And as I belive crash notifiers only will be used by a very limited
> > number of users, I suggested in another mail that a simple
> >
> > if (function pointer)
> >    call functon
> >
> > approach to be used for this special case to keep things very simple.
> 
> I am completely against crash notifiers.  The code crash_kexec switches to
> is what is notified and it can do whatever it likes.  The premise is
> that the kernel does not work.  Therefore  we cannot safely notify
> kernel code.  We do the very minimal to get out of the kernel,
> and it is my opinion we still do to much.
> 
> The crash_kexec entry point is not about taking crash dumps.  It is
> about implementing policy when the kernel panics.  Generally the
> policy we want is a crash dump but the mechanism is general purpose
> and not limited to that.

I understand it is more reliable that the notifier is executed
by crash_kexec(). But I guess it take longer time than a clustering
system demand and it is more complex to implement the notifier.
The crash notifier I proposed is very simple and lightweight,
and it is easy to use for all people.

Regards,

Akiyama, Nobuyuki