Intel XL710 broken link down detection?

[Steven Hartland]

Seems the Intel XL710 (ixl) has broken link detection, it triggers on 
link up but not on link down.

I'm currently running HEAD (r290610) on the box which has 1.4.3 and have 
tried the latest driver from downloads.intel.com which is listed as 
1.4.8 but reports 1.4.5.

We've updated to the latest NVM image today to see if that would help 
but no change.

Tracing with dtrace shows that ixl_do_adminq process a link event and 
fires off ixl_link_event for link up but not for link down for some reason.

Running ifconfig against the interface updates the status as runs 
ixl_update_link_status in ixl_media_status, so the device can determine 
the link is down its just not noticing the event.

 From dmesg:
ixl0: <Intel(R) Ethernet Connection XL710 Driver, Version - 1.4.3> mem 
0xc5000000-0xc57fffff,0xc5808000-0xc580ffff irq 34 at device 0.0 on pci5
ixl0: Using MSIX interrupts with 33 vectors
ixl0: f4.40 a1.4 n04.53 e80001ccc
ixl0: Using defaults for TSO: 65518/35/2048
ixl0: Ethernet address: 0c:c4:7a:3a:2d:60
ixl0: PCI Express Bus: Speed 8.0GT/s Width x8
queues is 0xfffffe00015bd000
ixl0: netmap queues/slots: TX 32/1024, RX 32/1024
ixl1: <Intel(R) Ethernet Connection XL710 Driver, Version - 1.4.3> mem 
0xc4800000-0xc4ffffff,0xc5800000-0xc5807fff irq 34 at device 0.1 on pci5
ixl1: Using MSIX interrupts with 33 vectors
ixl1: f4.40 a1.4 n04.53 e80001ccc
ixl1: Using defaults for TSO: 65518/35/2048
ixl1: Ethernet address: 0c:c4:7a:3a:2d:61
ixl1: PCI Express Bus: Speed 8.0GT/s Width x8
queues is 0xfffffe0001ad1000
ixl1: netmap queues/slots: TX 32/1024, RX 32/1024

When its up it reports 10GBase-KR

Any ideas?

     Regards
     Steve