xmon & SCSI ATA devices

xmon & SCSI ATA devices

[gshan]

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?

Thanks,
Gavin

Re: xmon & SCSI ATA devices

[Benjamin Herrenschmidt]

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...

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.

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
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

Re: xmon & SCSI ATA devices

[gshan]

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Re: xmon & SCSI ATA devices

[Benjamin Herrenschmidt]

On Tue, 2009-12-29 at 23:09 -0500, gshan wrote:

> 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.

Well, mostly xmon kicks in when you already oopsed or crashed so .. :-)

As I said, getting into the SCSI stack or similar would make the whole
thing extremely fragile. But you may want to hack something for
yourself, feel free to do so.

Cheers,
Ben.

Re: xmon & SCSI ATA devices

[gshan]

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