kern/118927: em(4) broken: link state changed to DOWN (/UP), link states coalesced errors

[Pekka Savola]

>Number:         118927
>Category:       kern
>Synopsis:       em(4) broken: link state changed to DOWN (/UP), link states coalesced errors
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Dec 21 11:00:00 UTC 2007
>Closed-Date:
>Last-Modified:
>Originator:     Pekka Savola
>Release:        6.3-PRERELEASE
>Organization:
>Environment:
FreeBSD sixpack.funet.fi 6.3-PRERELEASE FreeBSD 6.3-PRERELEASE #13: Fri Dec 21 10:18:44 EET 2007     root at sixpack.funet.fi:/usr/obj/usr/src/sys/SIXPACK  i386
>Description:
After upgrading via sources from 6.2-STABLE (Aug 7) to 6.3-PRERELEASE (snapshots from about November 29 and December 21 tested), em2 interface started spewing out the following ad infinitum:

em2: 32 link states coalesced
em2: link state changed to UP
em2: 19 link states coalesced
em2: link state changed to DOWN
em2: 3 link states coalesced
em2: link state changed to UP
em2: 17 link states coalesced
em2: link state changed to DOWN
em2: link state changed to UP
em2: 20 link states coalesced

The link led is blinking.  Fibers are not connected.

Rebooting to 6.2-STABLE from Aug 7 works.

This happens on an add-on card with 1000FX (multimode) adapter only.  Intel cards on the same system which have UTP interface are OK.

Unfortunately I had to plug off the card, but I inserted into a Linux and got the following information about it:

0b:01.0 Ethernet controller: Intel Corporation 82542 Gigabit Ethernet Controller (Fiber) (rev 02)

. but I guess that should be enough to figure out what's going on.

I suspect one of the em(4) driver updates broke this particular piece of hardware.

>How-To-Repeat:
Try to boot to a recent RELENG_6 kernel with Intel 82542 network card.
>Fix:
Fix not known.  Using 6.2-STABLE from Aug 7 2007 does not yet introduce the problem.

>Release-Note:
>Audit-Trail:
>Unformatted: