I have SUSE 11 SP4 VM, initially it was working on Xen in PV mode. Now I am moving it to KVM. My usual approach is to netboot any Linux in target VM, mount root of target OS, chroot and rebuild initramfs, then reboot VM into target OS.
SLES 11 SP4 seem to lack something because after that initramfs can't find any vbd device to mount root. However, I have managed to run it via direct qemu command on KVM host:
qemu-kvm -m 32768 -smp 8 -device virtio-net-pci,mac=42:5f:96:48:39:fa,netdev=vmnic -netdev tap,id=vmnic,script=/etc/ovs-ifup,downscript=/etc/ovs-ifdown -nographic -serial mon:stdio -drive file=/dev/lvm/vm,if=none,id=drive0,format=raw -device virtio-blk-pci,drive=drive0,scsi=off
and it works fine.
KVM config (disk-related) look like this:
<devices>
<emulator>/usr/bin/qemu-system-x86_64</emulator>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none" io="native"/>
<source dev="/dev/lvm/vm"/>
<target dev="vda" bus="virtio"/>
<address type="pci" domain="0x0000" bus="0x03" slot="0x00" function="0x0"/>
</disk>
<controller type="pci" index="3" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="3" port="0xa"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x2"/>
</controller>
and my virt-manager do not allow me to make significant changes here.
I might be wrong here, but I think the main difference is PCI devices structure so initramfs work in one way, but not in the other. I have compared PCI devices:
Device tree found on VM which was directly run via qemu command:
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]
00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
00:02.0 VGA compatible controller: Device 1234:1111 (rev 02)
00:03.0 Ethernet controller: Red Hat, Inc Virtio network device
00:04.0 SCSI storage controller: Red Hat, Inc Virtio block device
Device tree found on any other KVM VM (same host):
00:00.0 Host bridge: Intel Corporation 82G33/G31/P35/P31 Express DRAM Controller
00:01.0 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:01.1 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:01.2 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:01.3 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:01.4 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:01.5 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:01.6 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:01.7 PCI bridge: Red Hat, Inc. QEMU PCIe Root port
00:1f.0 ISA bridge: Intel Corporation 82801IB (ICH9) LPC Interface Controller (rev 02)
00:1f.2 SATA controller: Intel Corporation 82801IR/IO/IH (ICH9R/DO/DH) 6 port SATA Controller [AHCI mode] (rev 02)
00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 02)
01:00.0 Ethernet controller: Red Hat, Inc. Virtio network device (rev 01)
02:00.0 USB controller: Red Hat, Inc. QEMU XHCI Host Controller (rev 01)
03:00.0 SCSI storage controller: Red Hat, Inc. Virtio block device (rev 01)
04:00.0 Unclassified device [00ff]: Red Hat, Inc. Virtio memory balloon (rev 01)
05:00.0 Unclassified device [00ff]: Red Hat, Inc. Virtio RNG (rev 01)
08:00.0 SCSI storage controller: Red Hat, Inc. Virtio block device (rev 01)
Here I see the difference: qemu allow attaching storage to root PCI host bridge, but in KVM it is always attached to QEMU PCIe Root port.
My questions are:
- Is it possible that SLES 11 is too old to support QEMU PCIe Root port?
- Is it possible to ease VM configuration to attach storage to Host bridge directly?
- I rebuild initramfs in target environment, adding nothing to config files. Am I missing something (hooks or drivers) when rebuilding initramfs?
