Subject: Re: xmon & SCSI ATA devices

From: gshan <[email-masked]>
Date: Tue, 29 Dec 2009 23:09:21 -0500

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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