On Fri, 27 Aug 2021 18:48:04 +0200 Mark Kettenis <mark.kette...@xs4all.nl> wrote:
> > Date: Fri, 27 Aug 2021 18:02:59 +0200 > > From: Greg Kurz <gr...@kaod.org> > > > > On Fri, 27 Aug 2021 15:12:31 +0000 > > Joseph <joseph.ma...@protonmail.com> wrote: > > > > > On Friday, August 27th, 2021 at 11:01 PM, Greg Kurz <gr...@kaod.org> > > > wrote: > > > > Linux knows how to drive both powernv and pseries platforms. > > > .. > > > > OpenBSD might have to implement proper guest-side pseries > > > > support to run as a guest under an hypervisor on POWER. I don't > > > > know OpenBSD but this likely a huge effort. > > > > > > > > More details in the "Linux on POWER Architecture Reference": > > > > https://openpowerfoundation.org/wp-content/uploads/2020/07/LoPAR-20200611.pdf > > > > and under the arch/powerpc/platforms/pseries/ directory in the linux > > > > kernel sources. > > > > > > Hi Greg, > > > > > > Thanks for following up. > > > > > > (Meanwhile I posted this Q to KVM-PPC and QEMU-PPC too. On the latter > > > it's https://lists.nongnu.org/archive/html/qemu-ppc/2021-08/msg00416.html > > > and on the further it didn't register yet.) > > > > > > First I believe KVM-QEMU and "PowerKVM" are different - the latter was > > > a KVM fork maintained by IBM. The further is just the KVM and QEMU > > > repo. Did IBM their contributions so PowerKVM was upstreamed, you tell > > > me. > > > > > > > Yes you're right that PowerKVM was an IBM internal fork of KVM and > > QEMU, but it was discontinued ages ago. All the relevant bits have > > been merged upstream and all development since then happens upstream. > > So it doesn't make a big difference now to use PowerKVM instead of > > QEMU-KVM on POWER. > > > > > Are you saying that KVM-QEMU has all relevant Power9 support > > > already, for a Linux host OpenBSD as a guest on bare metal > > > ("powernv" mode)? > > > > > > > There's some confusion here. In bare metal, you just have a single > > instance of the OS running unvirtualized directly on the host. > > KVM-QEMU isn't involved at all in this case. According to the OpenBSD > > statement, you can already install and run it in this mode on an > > OpenPOWER system. > > Correct. > > > > In this case why would there be any relevance in OpenBSD implementing > > > pseries. > > > > > > > If you want to also run OpenBSD inside a VM, then OpenBSD must > > implement proper support to be able to run in the paravirtualized > > PAPR environment provided by KVM-QEMU on POWER. The OpenBSD statement > > seem to indicate this is missing. Nothing special "should" be needed > > on the KVM-QEMU side. > > Indeed. OpenBSD/powerpc64 currently does not implement PAPR > environment support. I've looked at it at some point and I don't > think adding support for it would be impossible. But I only have > powernv hardware. I suppose I could run KVM-QEMU on Linux on that but > my time is limited. > Yeah, KVM-QEMU can run on powernv hardware. So you could use it as a development environment to implement PAPR support in OpenBSD. This is clearly not something achievable if you only have limited time though. > It is possible to use QEMU to emulate a powernv machine and in > principle you can run OpenBSD in that environment on a Linux host. > But that's emulation and not virtualization. Yeah, no KVM in this case and it will be extremely slow. > It doesn't seem to work > though and the installer hangs after printing its first message. I > suspect QEMU's emulation of the XIVE interrupt controller isn't 100% > faithful. It's also really slow when running on an amd64 machine, so > I didn't investigate further. A lot of things can go wrong when it comes to boot a powernv platform :) Cc'ing Cedric who is the maintainer of XIVE and POWERNV in QEMU. Cheers, -- Greg
