more problems with em(4)

I reported problems to current_at_ about my problems with em(4) card on
CURRENT on a notebook where mostly everything is on one IRQ some time
ago. The problem manifests itself sometimes that the card stops working
and once the USB wasn't working at the same time. When I first noticed
it I didn't receive watchdog timeout messages but now I do. Scott Long
suggested that the problem might be in the new interrupt handling in the
driver and that I should try define NO_EM_FASTINTR. I couldn't say
whether that helped because I had run for quite some time with it
defined without card wedging and also for long time with the stock
driver.

Today I've updated one machine acting as a router to RELENG_6 and I've
also got several watchdog timeouts on the machine. One em card (em1)
shares the IRQ with USB (as on the notebook) whereas the other doesn't.

The machine didn't stop forwarding packets so it is probably a different
problem that the one with wedged card, possibly completely harmless. It
will be pretty bad if we shipped 6.1 with broken em(4) driver though.
The first watchdog message appeared after almost 2 hours of operation
(so it wasn't some stabilizing on boot or something). It has never
appeared before in more than a year with 5.x (the router is only lighly
loader - it pushes 1Mbps on average).

The em card in the notebook identifies itself in 'pciconf -lv' output as
"82540EP Gigabit Ethernet Controller (Mobile)" whereas on the router the
card is "82541EI Gigabit Ethernet Controller (Copper)".

Mar  6 21:56:26 sx-a kernel: em1: watchdog timeout -- resetting

I've changed the media settings of em0 from 100-full to auto here (em1
has been set to auto and runs 1000-full all the time).
Mar  7 01:35:45 sx-a kernel: em0: Link is up 100 Mbps Full Duplex

Mar  7 01:43:16 sx-a kernel: em0: watchdog timeout -- resetting
Mar  7 05:33:57 sx-a kernel: em1: watchdog timeout -- resetting

Verbose dmesg available on request.

I can experiment on the notebook but obviously not on the router.

Regards

Michal