I saw some messages that may or may not have anything to do with the problem. Note the one about IRQ21 being shared; it's not clear that it relates to any of the others, but the proximity (in time, too) makes me wonder.
How can I find out what drivers are sharing it? Nov 17 16:33:32 virtualbox-sxce pcplusmp: [ID 805372 kern.info] pcplusmp: pci80ee,cafe (vboxguest) instance 0 irq 0x14 vector 0x20 ioapic 0x2 intin 0x14 is bound to cpu 0 Nov 17 16:33:32 virtualbox-sxce ac97: [ID 750319 kern.info] audio810#0: AC'97 codec id SigmaTel STAC9700 (83847600, 2 channels, caps 0) Nov 17 16:33:32 virtualbox-sxce unix: [ID 954099 kern.info] NOTICE: IRQ21 is being shared by drivers with different interrupt levels. Nov 17 16:33:32 virtualbox-sxce This may result in reduced system performance. Nov 17 16:33:32 virtualbox-sxce pci: [ID 370704 kern.info] PCI-device: pci8086,0 at 5, audio8100 Nov 17 16:33:32 virtualbox-sxce genunix: [ID 936769 kern.info] audio8100 is /pci at 0,0/pci8086,0 at 5 -- This message posted from opensolaris.org
