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Re: [Xen-devel] kernel BUG look familiar?

To: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] kernel BUG look familiar?
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Sat, 15 Apr 2006 09:41:43 +0100
Cc: Matt Ayres <matta@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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> > This was reported by one of my users and it shows on every boot for 
> > them.  I wanted to know if this was a known issue before filing a bug 
> > report.
> I've never seen this. It looks fairly harmless, but worth understanding.
> Please can you post a full boot log, state what distro is being used in
> the domU, and whether tls has been disabled or whether 'echo "hwcap 0
> nosegneg" > /etc/ld.so.conf.d/xen' has been executed.

There's a 5-second pause the first time negative segment offsets are
used, to provide a clear warning to the user. The softlockup watchdog
is supposed to kick in after 10 seconds, so something here is a bit
confused. It's probably that mdelay() is delaying more than a
second. It's a software delay loop which we really ought to replace
with something better (HYPERVISOR_poll is the obvious candidate).

The issue can be worked around by calling touch_softlockup_watchdog()
in the 5-second delay loop in arch/i386/kernel/fixup.c.

 -- Keir

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