kern/93586: /src/sys/dev/em/if_em.c 1.112 breaks interfaces

[Chris Elsworth]

>Number:         93586
>Category:       kern
>Synopsis:       /src/sys/dev/em/if_em.c 1.112 breaks interfaces
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Feb 20 05:10:02 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Chris Elsworth
>Release:        7.0-CURRENT
>Organization:
>Environment:
FreeBSD netboot0.newzbin.com 7.0-CURRENT FreeBSD 7.0-CURRENT #6: Mon Feb 20 04:34:03 UTC 2006     root at netboot0.newzbin.com:/usr/obj/usr/src/sys/X4100_BOOTSRV  amd64 
>Description:
Upon supping to HEAD tonight, I found that my if_em's in the
Sun Fire x4100 I was fiddling on no longer brought up the link after
they were assigned an IP:

# ifconfig em1 && ifconfig em1 192.168.201.112 && sleep 5 && ifconfig em1
em1: flags=8802<BROADCAST,SIMPLEX,MULTICAST> mtu 1500
        options=8b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWCSUM>
        ether 00:14:4f:20:4f:2d
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        options=8b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWCSUM>
        inet 192.168.201.112 netmask 0xffffff00 broadcast 192.168.201.255
        ether 00:14:4f:20:4f:2d
        media: Ethernet autoselect
        status: no carrier

I realise there may be a nominal delay until the carrier comes back,
but it never does.

After some experimentation, I discovered that revision 1.112 is responsible
for this. If I check out 1.111 and build it as a module, the system is fine.

# kldunload if_em
# kldload if_em_1.111.ko
.
em1: <Intel(R) PRO/1000 Network Connection Version - 3.2.18> port 0x9800-0x983f mem 0xfbfc0000-0xfbfdffff irq 27 at device 1.1 on pci1
em1: Ethernet address: 00:14:4f:20:4f:2d
em1: [FAST]

# ifconfig em1 && ifconfig em1 192.168.201.112 && sleep 5 && ifconfig em1
em1: flags=8802<BROADCAST,SIMPLEX,MULTICAST> mtu 1500
        options=8b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWCSUM>
        ether 00:14:4f:20:4f:2d
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        options=8b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWCSUM>
        inet 192.168.201.112 netmask 0xffffff00 broadcast 192.168.201.255
        ether 00:14:4f:20:4f:2d
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active


>How-To-Repeat:
Use revision 1.112 of if_em.c
>Fix:
Maybe that hardware initialisation was required after all?
>Release-Note:
>Audit-Trail:
>Unformatted: