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Date: Tue, 27 Dec 2005 15:41:20 -0800
From: Nate Lawson <nate@root.org>
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To: Scott Long <scottl@samsco.org>
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Cc: cvs-src@FreeBSD.org, Gleb Smirnoff <glebius@FreeBSD.org>,
	cvs-all@FreeBSD.org, src-committers@FreeBSD.org
Subject: Re: cvs commit: src/sys/dev/em if_em.c
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Scott Long wrote:
> Nate Lawson wrote:
>> This probably means that the PCI memory space isn't fully initialized 
>> but an interrupt has been triggered.  If you then go and try to poke 
>> the hardware, then you can hang the system.
>>
> 
> I can believe your first statement, but not your second.  Hanging the
> system on an aborted memory read cycle (as opposed to just throwing a
> #SERR) would indicate a highly highly broken chipset.  In any case, if
> we ever implement PCI hotplug then we'll have to deal with the effects
> of aborted PCI transfers anyways.
> 
> Scott

It's not the PCI write that hangs the system, it's the behavior of the 
device written to.  It may never release the interrupt.  Using an NMI to 
debug would be good.

-- 
Nate