Comment 18 for bug 432154

all, here is as much information as I could think of in an attempt to allow for reproducability (see attached file). Here is what each file in the attached tarball contains:

setup - quick description of machine set up

orig.libvirt.xml - the XML vm description that is passed to libvirt
kvmcmdline - upon VM run, this is the kvm process (with cmdline arguments) that is actually running
dumpxml.libvirt.xml - virsh dumpxml output from running VM

i-42CC08B6.log.b4-attach - /var/log/libvirt/qemu/... logfile of the running VM before attach
vm_dmesg.b4-attach - dmesg output from inside VM before attach
vm_dmesg.after-attach - dmesg output from inside VM after attach
i-42CC08B6.log.after-attach - /var/log/libvirt/qemu/... logfile of the running VM after attach

attach-device.cmds - script of commands ran to attach disk
attach-device.xml - input to virsh attach-device

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with dustin's instuctions above (sending pci_add directly to KVM through the monitor), I was able to reproduce the problem when if=scsi. with if=virtio, the device shows up just fine.