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Date:      Sun, 17 May 1998 10:37:02 -0600
From:      "Justin T. Gibbs" <gibbs@plutotech.com>
To:        Mark Murray <mark@grondar.za>
Cc:        gibbs@FreeBSD.ORG, scsi@FreeBSD.ORG
Subject:   Re: CAM broken with SMP/current/AHC 
Message-ID:  <199805171641.KAA29693@pluto.plutotech.com>
In-Reply-To: Your message of "Sun, 17 May 1998 09:58:02 %2B0200." <199805170758.JAA00278@greenpeace.grondar.za> 

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>Hi
>
>I added the latest CAM snapshot diffs to my current tree and I
>get the following panic on boot:
>
>SMP: AP CPU#1 Launched!
>panic: ahc_intr: AWAITING_MSG for an SCB that does not have a waiting message
>mp_lock = 00000001; cpuid = 0; lapic.id = 00000000
>boot() called on CPU#0
>
>syncing disks... done
>Automatic reboot in 15 seconds - press any key on the console to abort
>
>Any ideas?

I started hunting around for where the system launches the other CPUs, but
I haven't found it yet.  My guess is that just at the point of startup, 
these CPUs are vulnerable to receiving interrupts at the same time as CPU 
0.  I've done some analysis with Russell Cattelan on this, and the only
way I can see for this error to occur is if one of the interrupt driver
lists is corrupted by unexpected interrupt re-entrance.

Why wouldn't this affect the old SCSI code?  CAM continues with the boot
process while still configuring the devices on the bus, but after 
registering the presence of the devices to the system.  This allows the
boot to block only during the configuration of the devices it cares about
(like your root disk).  But, this does open the window for I/O to occur
while extra CPUs are started.

>M
>-- 
>Mark Murray
>Join the anti-SPAM movement: http://www.cauce.org

--
Justin



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