You also need to tell the guest that a new device exists... Unless it (the guest) has some hotswap abilities....
Do you know how I can do that?
I reinstalled the guest (CentOS 5.4 x86_64, just as the host) with the default non-desktop groups, but it still doesn't see when I attach a disk.
I also try to disable SELinux, to no effect.
I've googling intensively around the concept of hotplug, hotswap, PCI, HAL, etc. in relation to virsh/KVM/virtio but withotu success.
On the guest, lspci only shows on drive (the initial one I guess):
[root@localhost ~]# lspci 00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02) 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II] 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II] 00:01.2 USB Controller: Intel Corporation 82371SB PIIX3 USB [Natoma/Triton II] (rev 01) 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03) 00:02.0 VGA compatible controller: Cirrus Logic GD 5446 00:03.0 Ethernet controller: Qumranet, Inc. Virtio network device 00:04.0 SCSI storage controller: Qumranet, Inc. Virtio block device 00:05.0 RAM memory: Qumranet, Inc. Virtio memory balloon