I'd prefer to fix it with the diff below, to help the diffability with
the amd64 codebase.
Index: pci_machdep.c
===================================================================
RCS file: /cvs/src/sys/arch/i386/pci/pci_machdep.c,v
retrieving revision 1.64
diff -u -p -r1.64 pci_machdep.c
--- pci_machdep.c 13 Oct 2011 18:09:33 -0000 1.64
+++ pci_machdep.c 4 Dec 2011 19:24:43 -0000
@@ -212,6 +212,13 @@ pci_attach_hook(struct device *parent, s
return;
/*
+ * Machines that use the non-standard method of generating PCI
+ * configuration cycles are way too old to support MSI.
+ */
+ if (pci_mode == 2)
+ return;
+
+ /*
* In order to decide whether the system supports MSI we look
* at the host bridge, which should be device 0 function 0 on
* bus 0. It is better to not enable MSI on systems that
