Issues with 'xl0' keeping link

[Kevin Gerry]

I've noticed that after a recent patch, that xl0 is having issues syncing
(Example from log/messages below) and wasn't sure how to 'debug' the
interface to find out what either physically or if the driver is causing it.
(I have attempted replacing the card with the same model)

/var/log/messages:
Jun 25 18:10:20 storage kernel: xl0: link state changed to DOWN
Jun 25 18:10:22 storage kernel: xl0: link state changed to UP
Jun 25 18:11:30 storage kernel: xl0: link state changed to DOWN
Jun 25 18:11:31 storage kernel: xl0: link state changed to UP
Jun 25 18:12:15 storage kernel: xl0: link state changed to DOWN
Jun 25 18:12:17 storage kernel: xl0: link state changed to UP
Jun 25 18:12:38 storage kernel: xl0: link state changed to DOWN
Jun 25 18:12:39 storage kernel: xl0: link state changed to UP

pciconf:
xl0 at pci0:10:0:  class=0x020000 card=0x100010b7 chip=0x980510b7 rev=0x78
hdr=0x00
    vendor     = '3COM Corp, Networking Division'
    device     = '3C980-TX 10/100baseTX NIC [Python-T]'