Newsgroups: fa.linux.kernel
From: Linus Torvalds <torvalds@osdl.org>
Subject: Re: 2.6.0-test9-mm3
Original-Message-ID: <Pine.LNX.4.44.0311141344290.5877-100000@home.osdl.org>
Date: Fri, 14 Nov 2003 21:48:59 GMT
Message-ID: <fa.jjta19r.1gl80h1@ifi.uio.no>

On Fri, 14 Nov 2003, Martin J. Bligh wrote:
>
> Linus had some debug thing for triple faults, a few months ago, IIRC ...
> probably in the archives somewhere ...

Triple faults you can't debug, they raise a line outside the CPU, and
normal PC hardware will cause that to just trigger a reboot.

But double faults do get caught, and that debugging stuff actually is in
the standard kernel. It won't give _nearly_ as good a debug report as a
"normal" oops, since I didn't want the double-fault handler to touch
anything even remotely unsafe, but it often gives a good hint about what
might be wrong. Certainly better than triple-faulting did (which we still
do for _catastrophic_ corruption, eg totally munged kernel page tables etc
- it's just very hard to avoid once you get corrupted enough).

		Linus