From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cnshjsmin03.cn.alcatel-lucent.com (cnmailgate04.alcatel-sbell.com.cn [211.144.215.47]) by ozlabs.org (Postfix) with ESMTP id 6892DB6EEF for ; Wed, 30 Dec 2009 02:10:42 +1100 (EST) Message-ID: <4B3AD271.1050105@alcatel-lucent.com> Date: Tue, 29 Dec 2009 23:09:21 -0500 From: gshan MIME-Version: 1.0 To: Benjamin Herrenschmidt Subject: Re: xmon & SCSI ATA devices References: <4B33197D.9000506@alcatel-lucent.com> <1262079428.2173.218.camel@pasglop> In-Reply-To: <1262079428.2173.218.camel@pasglop> Content-Type: text/html; charset=UTF-8 Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Benjamin Herrenschmidt wrote:

On Thu, 2009-12-24 at 02:34 -0500, gshan wrote:

Hello,

xmon and SCSI SATA device driver were installed on my system. When I invoked
xmon explicitly for kernel debugging, there're probably pending SCSI 
requests issued.
So those SCSI requests complained timeout when I quited from xmon. I want to
find a way to suspend SCSI device before invoking xmon and resume that 
before
quiting from xmon. Anybody knew there is a way to do this?


Well, it's non trivial. xmon is very low level and doesn't muck around
with drivers etc...

Yes. I agree.

We could add hacks to avoid those timeouts or even do what you suggest
with suspending devices, but that would make entering xmon a -lot- more
fragile. The idea is that xmon relies on very little kernel services and
can be entered even when things are utterly wrong.

Actually, the situation I described above has caused lots of disk issue.
The DPT (disk partition table) might be lost because of this. I think it's
broken the rule: xmon is assisting to resolve kernel issue, not cause
more.

To be honest, I'm tempted to leave that as it is. Most of the time,
getting into xmon is a one way trip....

Cheers,
Ben.

Thanks,
Gavin
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