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Message-Id: <200705160723.l4G7N5Rp095206@www.freebsd.org>
Date: Wed, 16 May 2007 07:23:05 GMT
From: Arthur Hartwig<arthur.hartwig@nokia.com>
To: freebsd-gnats-submit@FreeBSD.org
Subject: emdriver doesn't use MSI on MSI capable device
X-Send-Pr-Version: www-3.0

>Number:         112702
>Category:       kern
>Synopsis:       [em] em driver doesn't use MSI on MSI capable device
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    jfv
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed May 16 07:30:04 GMT 2007
>Closed-Date:    
>Last-Modified:  Wed May 16 14:19:31 GMT 2007
>Originator:     Arthur Hartwig
>Release:        FreeBSD 7
>Organization:
Nokia
>Environment:
FreeBSD oz-net-11.nes.nokia.com 7.0-CURRENT FreeBSD 7.0-CURRENT #4: Fri May 11
11:56:18 EST 2007     root@oz-net-11.nes.nokia.com:/usr/obj/usr/src/sys/FBSD_TM
PFS  i386

>Description:
FreeBSD 7 built a few weeks ago used MSI on two MSI capable interfaces
(82572 chips). 

The recent substantial changes to emdriver have broken emdriver's use of MSI.
Inspection of if_em.c shows em_attach() calls em_allocate_pci_resources()
which for a 82572 based NIC to use MSI ends up requiring the bus.type field
in the adapter structure to be set to e1000_bus_type_pci_express. However
the bus type is not initialised until the call to e1000_get_bus_info() which
is called AFTER em_attach() calls em_allocate_pci_resources().

I have been investigating the use of MSI to avoid interrupt sharing in a
new system with a significant number of PCI express NICs.
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
Responsible-Changed-From-To: freebsd-bugs->jfv 
Responsible-Changed-By: remko 
Responsible-Changed-When: Wed May 16 14:19:27 UTC 2007 
Responsible-Changed-Why:  
Over to maintainer. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=112702 
>Unformatted:
