Comment 6 for bug 458201

Ok, I've verified this is still present in lucid.
On lucid beta1 kvm, with lucid beta-1 server install

# create a disk image
truncate 10M /tmp/my.img

# launch kvm, watch it boot
kvm -drive file=sda.img,if=scsi,index=0,boot=on -drive file=sdb.img,if=scsi,index=1 -m 512

# in kvm guest, do
$ sudo modprobe acpi_php
# dmesg | tail will now show evidence of something (slot...)

# in kvm monitor, do
% pci_add auto storage file=/tmp/my.img,if=scsi
OK domain 0, bus 0, slot 5, function 0

# in kvm guest, /proc/partitions should now have a new entity (/dev/sdc)
# make a filesystem there, mount, write, unmount
$ sudo mke2fs /dev/sdc
$ sudo mount /dev/sdc /mnt
$ sudo sh -c 'echo hi mom > /mnt/foo'
$ sudo umount /mnt

# in the kvm monitor, detach the device
% pci_del 0:5

# in the kvm guest, now dmesg will show traceback failure