[3c509] Cannot bring up two 3c509 cards

[J. David Blackstone]

  I've added a second 3c509 to my RedHat 7.2 system, and I cannot seem to 
get both cards activated.

  dmesg reports both cards as being IRQ 5.  How can I tell the second card
to use a different IRQ?  I've specified a different one in
/etc/modules.conf, as suggested in the Ethernet HOWTO:

alias eth0 3c509
alias eth1 3c509
options eth0 -o 3c509-0 irq=5
options eth1 -o 3c509-1 irq=7

  Both cards work.  RedHat ifconfigs eth0 correctly on startup.  I can
ifconfig it down and then bring up eth1.  But I cannot bring up eth1 when
eth0 is up.  The message I get is:
SIOCSIFFLAGS: Device or resource busy

  RedHat's config tool (linuxconf) seems to be no help, so far.

  I'm looking at the isapnp utilities trying to find a way to change the
IRQ.  Am I looking in the right place?

J. David Blackstone