Delving further into the PCI->CardBus bridge, I noticed that my system locks up under certain conditions when the yenta_socket driver is trying to probe for PCMCIA ISA interrupts. yenta_get_socket_capabilities() calls probe_irq_on() in arch/mips/kernel/irq.c. The lock up happens when the probe performs the first iteration over the IRQ descriptors, looking for longstanding IRQs. I added some debugging output, and it get down to IRQ 34, and then stopped. (AU1000 GPIO pin 2? this pin isn't connected on our board... ) Anyhow, when the probe *does* succeed, the IRQ poll returns 0x0000. I guess my question is, why even bother with this polling on a machine without an ISA bus? I believe that the CardBus bridge PCI configuration registers route socket events to the PCI INTA pin anyway... My happy hack is to have yenta_get_socket_capabilities always return 0x0. But I'm still concerned that probe_irq_on() intermittently fails... Thanks for letting me interrupt you with this question. Regards, Jeff -- Jeffrey Baitis - Associate Software Engineer Evolution Robotics, Inc. 130 West Union Street Pasadena CA 91103 tel: 626.535.2776 | fax: 626.535.2777 | baitisj@evolution.com