Hi Cédric, On Thu, Nov 21, 2019 at 05:23:40PM +0100, Cédric Le Goater wrote: > The BMC of the OpenPOWER systems monitors the machine state using > sensors, controls the power and controls the access to the PNOR flash > device containing the firmware image required to boot the host. > > QEMU models the power cycle process, access to the sensors and access > to the PNOR device. But, for these features to be available, the QEMU > PowerNV machine needs two extras devices on the command line, an IPMI > BT device for communication and a BMC backend device: > > -device ipmi-bmc-sim,id=bmc0 -device isa-ipmi-bt,bmc=bmc0,irq=10 > > The BMC properties are then defined accordingly in the device tree and > OPAL self adapts. If a BMC device and an IPMI BT device are not > available, OPAL does not try to communicate with the BMC in any > manner. This is not how real systems behave. > > To be closer to the default behavior, create an IPMI BMC simulator > device and an IPMI BT device at machine initialization time. We loose > the ability to define an external BMC device but there are benefits: > > - a better match with real systems, > - a better test coverage of the OPAL code, > - system powerdown and reset commands that work, > - a QEMU device tree compliant with the specifications (*). > > (*) Still needs a MBOX device. > > Signed-off-by: Cédric Le Goater <c...@kaod.org>
I just started testing QEMU v5.0.0-rc1 against the little Linux booting framework that I helped set up for ClangBuiltLinux and this commit has caused some problems because we specify the exact same devices as you note in the commit message: https://github.com/ClangBuiltLinux/boot-utils/blob/5d9d3f626940a6a176c080717a367c1599f63680/boot-qemu.sh#L154-L155 $ timeout 3m unbuffer qemu-system-ppc64 -device ipmi-bmc-sim,id=bmc0 \ -device isa-ipmi-bt,bmc=bmc0,irq=10 \ -L images/ppc64le/ \ -bios skiboot.lid \ -machine powernv \ -display none \ -initrd images/ppc64le/rootfs.cpio \ -kernel zImage.epapr \ -m 2G \ -serial mon:stdio qemu-system-ppc64: error creating device tree: node: FDT_ERR_EXISTS It seems to me like if the machine is silently creating these devices, it should just warn that the user is trying to create a device that already exists? If not, then I assume I will just need to hack up a check for QEMU 5.0.0+ and just not add those devices? We use that script with QEMU 3.1.0 in our CI and I use it locally with QEMU 4.2.0 so universally getting rid of them doesn't seem logical. Curious for your thoughts on what to do and cheers, Nathan
