fxp multicast forwarding problems

Bruce M Simpson bms at incunabulum.net
Tue Sep 23 09:46:27 UTC 2008


Whilst doing some QA work on XORP on my desktop, which has fxp0 and 
msk0, fxp0 got totally hosed.
I was running PIM-SM and IGMPv2 router-mode on the box at the time.

I wonder if this is related to the problems with fxp multicast 
transmission I saw back in April.
I'm a bit concerned about this as fxp is still a very widespread and 
useful network chip.

I am running 7.0-RELEASE-p4/amd64.
sysctls for dev.fxp.0 are set to their default values.

I'm not expert on the fxp driver internals, but perhaps someone else has 
seen this kind of problem before. Multicast-promiscuous mode (aka 
ALLMULTI) was enabled on the interface. I know some NICs have problems 
with this, or don't even support it.

The errors look like this:
fxp0: SCB timeout: 0x10 0x0 0x80 0x0
fxp0: SCB timeout: 0x10 0x0 0x80 0x0
fxp0: DMA timeout
... repeated ...

Attempted workarounds which don't work to un-wedge the chip:
 Reload the fxp0 microcode with "ifconfig fxp0 link0"
 Forcibly unloading the kernel module and reloading it
 Unpatching and repatching at the switch (a cheap 10/100 one)
 Enabling and disabling promiscuous mode
 Twiddling dev.fxp.0.noflow

The link status looks fine, but the card will not send or receive traffic.
A warm reboot was enough to get things back up again.


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