Finally after a protracted struggle going on since about August 2005, Stephen Hemminger <firstname.lastname@example.org> the sky2 linux card driver author has finally figured out what it is that causes my sky2 card to work so sporadically. It seems that the linux kernel option CONFIG_PROFILING completely hoses the sky2 driver:
diff -u 2.6.15-rc1-mm1.config 2.6.15-rc2-mm1.config
# Instrumentation Support
+# CONFIG_PROFILING is not set
# CONFIG_KPROBES is not set
The 2.6.15-rc1-mm1 release did not work, 2.6.15-rc2-mm1 works just fine.
Totally weird, really. The symptoms were that the sky2 card would start up, work for a few seconds, then hang on the receive side, so would transmit data but not hear anything coming back in.
Thanks heaps to Stephen for spending the time to figure it out for me.
Now I have Gigabit Ethernet from my server to the rest of the network. Probably won't make a whole lot of difference especially with Internet traffic, but it's always nice when gear works the way it should do.
Update: I stopped using this device in May 2006 - I managed to get my hands on an Intel D945GNT motherboard which has an Intel E1000 onboard. I am no longer using the D925CVX board with the integrated SKY2 controller.
Update 2: One user has kindly emailed me to report that as of now, March 2007, there are still some ongoing and potentially nasty issues with this driver. At the time I was using it I never hammered it hard, but it seems there are ongoing issues of the card locking up under heavy transmit load. Therefore if you are looking at using a device with this ethernet chip, I recommend you research it - and if you can, be prepared to help the author improve and fix the problems with it.
More information can be found here: