Rapid link state changes on bge(4) interface

[David Christensen]

> I'm testing network failover on IBM BladeCenter running FreeBSD 6.1
> STABLE for Sep 6th.
> 
> I suspect a problem with link state change detection in bge code. When
> I disable internal port on chassis built-in ethernet switch, kernel
> floods syslog with messages about link state changes and coalescing
> them. Log snippet follows:
> 
> Sep 13 14:58:28 w3-6 kernel: bge1: link state changed to DOWN
> Sep 13 14:58:28 w3-6 kernel: bge1: link state changed to UP
> Sep 13 14:58:29 w3-6 kernel: bge1: link state changed to DOWN
> Sep 13 14:58:29 w3-6 kernel: bge1: link state changed to UP
> Sep 13 14:58:29 w3-6 kernel: bge1: link state changed to DOWN
> Sep 13 14:58:29 w3-6 kernel: bge1: 4 link states coalesced
> Sep 13 14:58:29 w3-6 kernel: bge1: link state changed to DOWN
> Sep 13 14:58:29 w3-6 kernel: bge1: 11 link states coalesced
> Sep 13 14:58:29 w3-6 kernel: bge1: link state changed to UP
> Sep 13 14:58:30 w3-6 kernel: bge1: link state changed to DOWN
> Sep 13 14:58:30 w3-6 kernel: bge1: 3 link states coalesced
> Sep 13 14:58:30 w3-6 kernel: bge1: link state changed to UP
> Sep 13 14:58:30 w3-6 kernel: bge1: 7 link states coalesced
> Sep 13 14:58:30 w3-6 kernel: bge1: link state changed to DOWN
> Sep 13 14:58:30 w3-6 kernel: bge1: 4 link states coalesced
> Sep 13 14:58:30 w3-6 kernel: bge1: link state changed to DOWN
> Sep 13 14:58:30 w3-6 kernel: bge1: 2 link states coalesced
> 
> As you can see, messages are generated in rapid succession and
> therefore any probing of link state change by ng_one2many for
> interface failover is meaningless. Ethernet switch doesn't register
> and log any interface state changes after disabling this port. LS20
> blades use chipset 8850. My firmware is 3.38, full changelog, if it is
> of any help, is here:
> 
> http://www-307.ibm.com/pc/support/site.wss/license.do?filename
=pc_servers/brcm_fw_nic_12021_anyos_anycpu.chg
> 
> Any ideas what might be wrong?

I can't access the information on this web site through Mozilla after
clicking "I Accept".  Is this a 5704 controller using a SerDes link?
I'm familiar with some Blade Center problems in the past (which I
think were related to Sigdet) though I'm not in the office and can't 
look into it right away.  A comparison between the serdes code in
the Linux driver vs. the FreeBSD driver is probably the first area to
investigate.

Dave