On Sat, Aug 28, 2021 at 10:46:52AM +0200, Cédric Le Goater wrote: > Hello, > > On 8/27/21 7:00 PM, Greg Kurz wrote: > > 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. > > KVM is supported under the QEMU PowerNV machine. I would not say it > is fast (clearly not) but guests start under the emulated hypervisor. > The emulated hypervisor it self can sustain a network bandwidth of > 10MB/s running on a small laptop which is quite fast for emulation. > > Anyhow, the QEMU PowerNV is a dev/test platform and not a production > one > > We do use the pseries XIVE emulation in prod on some P9 systems. > > >> It doesn't seem to work > >> though and the installer hangs after printing its first message. > > Can you send the command line ? > > >> I suspect QEMU's emulation of the XIVE interrupt controller isn't 100% > >> faithful. > > It is for pseries. PowerNV takes some shortcuts but it has enough support. > > >> It's also really slow when running on an amd64 machine, > > Compared to real HW. Yes :) > > >> so I didn't investigate further. > > Here are some docs : > > https://qemu.readthedocs.io/en/latest/system/ppc/powernv.html > > But if you have a real POWER9 system available, I would just install > the latest debian, ubunutu or fedora distros to run KVM guests. All > is merged. Working your way through the PAPR interface is going to > take some time, though. see the pseries platform under Linux.
I think this is missing the point. IIUC, Jospeh wants to run OpenBSD
as a *guest* not a host.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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