Fatal trap 19: non-maskable interrupt trap while in kernel mode

Matthew Dillon dillon at apollo.backplane.com
Fri Nov 5 12:20:12 PST 2004

    I think what is going on is that the probe code is unmasking the
    transmit and receive channel interrupts in order to probe the number
    of available channels, without first clearing any 'garbage' status
    pending on those channel(s).  Such status might occur from, e.g. the BIOS
    playing with the firewire controller before booting the system.

    This could result in an immediate interrupt which crashes the machine
    before the driver has had a chance to program the interrupt vector.

    If that is what is going on, then this patch should fix the problem.
    But it needs to be tested.  It doesn't crash my test box but we need to
    find out if it fixes the reported problem.

    Gabor, from your latest email it looks like neither NetBSD nor OpenBSD
    are running a firewire driver, so it is possible that they also have
    the bug but it isn't being hit.

    If you have the ability to download an ISO and burn it onto a CD to
    boot/test the fix I could generate an ISO image for you to try with this
    patch.  It may or may not work but it is worth a shot.


Index: fwohci.c
RCS file: /cvs/src/sys/bus/firewire/fwohci.c,v
retrieving revision 1.8
diff -u -r1.8 fwohci.c
--- fwohci.c	2 Jun 2004 14:42:48 -0000	1.8
+++ fwohci.c	5 Nov 2004 20:11:34 -0000
@@ -613,14 +613,17 @@
 /* Available Isochrounous DMA channel probe */
+	OWRITE(sc, OHCI_IT_STATCLR, 0xffffffff);
+	OWRITE(sc, OHCI_IR_STATCLR, 0xffffffff);
 	OWRITE(sc, OHCI_IT_MASK, 0xffffffff);
 	OWRITE(sc, OHCI_IR_MASK, 0xffffffff);
 	OWRITE(sc, OHCI_IT_MASKCLR, 0xffffffff);
 	OWRITE(sc, OHCI_IR_MASKCLR, 0xffffffff);
-	for (i = 0; i < 0x20; i++)
+	for (i = 0; i < 0x20; i++) {
 		if ((reg & (1 << i)) == 0)
+	}
 	sc->fc.nisodma = i;
 	device_printf(dev, "No. of Isochronous channel is %d.\n", i);
 	if (i == 0)

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