linux-kernel - Re: sleep before boot panic

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Message-ID: <20080108160645.GA4574@ucw.cz>
Date:	Tue, 8 Jan 2008 16:06:45 +0000
From:	Pavel Machek <pavel@....cz>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Oeser <ioe-lkml@...eria.de>, Andi Kleen <andi@...stfloor.org>,
	Bernd Schubert <bernd-schubert@....de>,
	linux-kernel@...r.kernel.org
Subject: Re: sleep before boot panic

Hi!

> >>>I just switched to libata (pata) on my laptop and the 
> >>>immediate panic made it impossible to figure out why 
> >>>my boot partition wasn't available.
> >>>After applying this little patch I could check boot 
> >>>printk output and then saw everything was properly 
> >>>recognized and only scsi-disk support was missing.
> >>The correct fix would be to make scroll back (and 
> >>sysrq) still work
> >>after panic.  It's a little more complicated, but 
> >>possible (essentially
> >>it needs a polled keyboard handler)
> >
> >Customer: "This system could not find the root fs."
> >Support: "Oh, yeah, just connect a (USB-) keyboard and 
> >scroll back."
> >
> >Hmm, device detection works after panic?
> >
> >I really like the "soft" panic better, where you still 
> >can operate the kernel debugging features, but just 
> >have no user space supporting it.

ACK. 'scheduling in interrupt' is very different from 'cant mount
root'.

> Of course, if we'd been using kinit, "soft panic" would 
> have been done exclusively in userspace...

What's the status of kinit, btw?
							Pavel
-- 
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