PowerNV family boards (powernv8, powernv9)

PowerNV (as Non-Virtualized) is the “baremetal” platform using the OPAL firmware. It runs Linux on IBM and OpenPOWER systems and it can be used as an hypervisor OS, running KVM guests, or simply as a host OS.

The PowerNV QEMU machine tries to emulate a PowerNV system at the level of the skiboot firmware, which loads the OS and provides some runtime services. Power Systems have a lower firmware (HostBoot) that does low level system initialization, like DRAM training. This is beyond the scope of what QEMU addresses today.

Supported devices

  • Multi processor support for POWER8, POWER8NVL and POWER9.
  • XSCOM, serial communication sideband bus to configure chiplets
  • Simple LPC Controller
  • Processor Service Interface (PSI) Controller
  • Interrupt Controller, XICS (POWER8) and XIVE (POWER9)
  • POWER8 PHB3 PCIe Host bridge and POWER9 PHB4 PCIe Host bridge
  • Simple OCC is an on-chip microcontroller used for power management tasks
  • iBT device to handle BMC communication, with the internal BMC simulator provided by QEMU or an external BMC such as an Aspeed QEMU machine.
  • PNOR containing the different firmware partitions.

Missing devices

A lot is missing, among which :

  • POWER10 processor
  • XIVE2 (POWER10) interrupt controller
  • I2C controllers (yet to be merged)
  • NPU/NPU2/NPU3 controllers
  • EEH support for PCIe Host bridge controllers
  • NX controller
  • VAS controller
  • chipTOD (Time Of Day)
  • Self Boot Engine (SBE).
  • FSI bus

Firmware

The OPAL firmware (OpenPower Abstraction Layer) for OpenPower systems includes the runtime services skiboot and the bootloader kernel and initramfs skiroot. Source code can be found on GitHub:

Prebuilt images of skiboot and skiboot are made available on the OpenPOWER site. To boot a POWER9 machine, use the witherspoon images. For POWER8, use the palmetto images.

QEMU includes a prebuilt image of skiboot which is updated when a more recent version is required by the models.

Boot options

Here is a simple setup with one e1000e NIC :

$ qemu-system-ppc64 -m 2G -machine powernv9 -smp 2,cores=2,threads=1 \
-accel tcg,thread=single \
-device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02,bus=pcie.0,addr=0x0 \
-netdev user,id=net0,hostfwd=::20022-:22,hostname=pnv \
-kernel ./zImage.epapr  \
-initrd ./rootfs.cpio.xz \
-nographic

and a SATA disk :

-device ich9-ahci,id=sata0,bus=pcie.1,addr=0x0 \
-drive file=./ubuntu-ppc64le.qcow2,if=none,id=drive0,format=qcow2,cache=none \
-device ide-hd,bus=sata0.0,unit=0,drive=drive0,id=ide,bootindex=1 \

Complex PCIe configuration

Six PHBs are defined per chip (POWER9) but no default PCI layout is provided (to be compatible with libvirt). One PCI device can be added on any of the available PCIe slots using command line options such as:

-device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02,bus=pcie.0,addr=0x0
-netdev bridge,id=net0,helper=/usr/libexec/qemu-bridge-helper,br=virbr0,id=hostnet0

-device megasas,id=scsi0,bus=pcie.0,addr=0x0
-drive file=./ubuntu-ppc64le.qcow2,if=none,id=drive-scsi0-0-0-0,format=qcow2,cache=none
-device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=2

Here is a full example with two different storage controllers on different PHBs, each with a disk, the second PHB is empty :

$ qemu-system-ppc64 -m 2G -machine powernv9 -smp 2,cores=2,threads=1 -accel tcg,thread=single \
-kernel ./zImage.epapr -initrd ./rootfs.cpio.xz -bios ./skiboot.lid \
\
-device megasas,id=scsi0,bus=pcie.0,addr=0x0 \
-drive file=./rhel7-ppc64le.qcow2,if=none,id=drive-scsi0-0-0-0,format=qcow2,cache=none \
-device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=2 \
\
-device pcie-pci-bridge,id=bridge1,bus=pcie.1,addr=0x0 \
\
-device ich9-ahci,id=sata0,bus=bridge1,addr=0x1 \
-drive file=./ubuntu-ppc64le.qcow2,if=none,id=drive0,format=qcow2,cache=none \
-device ide-hd,bus=sata0.0,unit=0,drive=drive0,id=ide,bootindex=1 \
-device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02,bus=bridge1,addr=0x2 \
-netdev bridge,helper=/usr/libexec/qemu-bridge-helper,br=virbr0,id=net0 \
-device nec-usb-xhci,bus=bridge1,addr=0x7 \
\
-serial mon:stdio -nographic

You can also use VIRTIO devices :

-drive file=./fedora-ppc64le.qcow2,if=none,snapshot=on,id=drive0 \
-device virtio-blk-pci,drive=drive0,id=blk0,bus=pcie.0 \
\
-netdev tap,helper=/usr/lib/qemu/qemu-bridge-helper,br=virbr0,id=netdev0 \
-device virtio-net-pci,netdev=netdev0,id=net0,bus=pcie.1 \
\
-fsdev local,id=fsdev0,path=$HOME,security_model=passthrough \
-device virtio-9p-pci,fsdev=fsdev0,mount_tag=host,bus=pcie.2

Multi sockets

The number of sockets is deduced from the number of CPUs and the number of cores. -smp 2,cores=1 will define a machine with 2 sockets of 1 core, whereas -smp 2,cores=2 will define a machine with 1 socket of 2 cores. -smp 8,cores=2, 4 sockets of 2 cores.

BMC configuration

OpenPOWER systems negotiate the shutdown and reboot with their BMC. The QEMU PowerNV machine embeds an IPMI BMC simulator using the iBT interface and should offer the same power features.

If you want to define your own BMC, use -nodefaults and specify one on the command line :

-device ipmi-bmc-sim,id=bmc0 -device isa-ipmi-bt,bmc=bmc0,irq=10

The files palmetto-SDR.bin and palmetto-FRU.bin define a Sensor Data Record repository and a Field Replaceable Unit inventory for a palmetto BMC. They can be used to extend the QEMU BMC simulator.

-device ipmi-bmc-sim,sdrfile=./palmetto-SDR.bin,fruareasize=256,frudatafile=./palmetto-FRU.bin,id=bmc0 \
-device isa-ipmi-bt,bmc=bmc0,irq=10

The PowerNV machine can also be run with an external IPMI BMC device connected to a remote QEMU machine acting as BMC, using these options :

-chardev socket,id=ipmi0,host=localhost,port=9002,reconnect=10 \
-device ipmi-bmc-extern,id=bmc0,chardev=ipmi0 \
-device isa-ipmi-bt,bmc=bmc0,irq=10 \
-nodefaults

NVRAM

Use a MTD drive to add a PNOR to the machine, and get a NVRAM :

-drive file=./witherspoon.pnor,format=raw,if=mtd

CAVEATS

  • No support for multiple HW threads (SMT=1). Same as pseries.
  • CPU can hang when doing intensive I/Os. Use -append powersave=off in that case.