[tulip] Quad card shares same irq on all ports, but only the first works

Alexander Havšng alexander@netintact.se
Thu Aug 1 05:29:01 2002


We have a problem with quad cards on a specific motherboard where all the
ports are assigned the same irq.
This should be fine, but on all other motherboards we've tried, each port gets its own irq, when available.

Now, here comes the weird part. Only when packets arrive on the first port interupts are actually raised. So if the first port is not receiving any packets, neither will the other ones.

If we keep nuking the first port with a stream of packets, the card works fine :)

This is simple to check with vmstat -n 1 or something, and no interrupts are raised for ports 1-3, only for port 0.

We're using a 21143 quad card from Phobos, and have also tried the DLink DFE-570TX card, with the same results.
The motherboard is a SuperMicro MBD-P4DP6-Q0, dual 2 GHz Xeon with PCI-X and lots of candy.

Any ideas on why the IRQ handling is fscked?