kern/105768: MSI triggers em0 watchdog failures

[Joe Marcus Clarke]

>Number:         105768
>Category:       kern
>Synopsis:       MSI triggers em0 watchdog failures
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Nov 23 08:30:16 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Joe Marcus Clarke
>Release:        FreeBSD 7.0-CURRENT
>Organization:
>Environment:
FreeBSD fugu.marcuscom.com 7.0-CURRENT FreeBSD 7.0-CURRENT #83: Thu Nov
23 01:51:05 EST 2006 root at fugu.marcuscom.com:/space2/obj/usr/src/sys/FUGU  i386


	
>Description:
I just synced with today's -CURRENT, and rendered by port build machine
useless.  With minimal network traffic (just logging in via SSH with a
TCP NFS-mounted home) I get an immediate watchdog timeout on em0, and
they just keep coming as I type in the session.  The machine is
otherwise idle while this is occurring.

Verbose dmesg : http://www.marcuscom.com/downloads/fugu_dmesg.txt
Kernel config : http://www.marcuscom.com/downloads/fugu_kernel.txt

Disabling MSI via hw.pci.enable_msi="0" resolves the problem.  Note:
keeping MSI-X enabled does not trigger the problem.  However, enabling
MSI and disabling MSI-X also triggers the problem.
>How-To-Repeat:
>Fix:
Adding hw.pci.enable_msi="0" to /boot/loader.conf works around the
problem.
>Release-Note:
>Audit-Trail:
>Unformatted: