[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [RFC PATCH] Disable Book-E KVM support?

From: Christian Zigotzky
Subject: Re: [RFC PATCH] Disable Book-E KVM support?
Date: Sun, 4 Dec 2022 12:33:26 +0100
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.5.1

Hi All,

We regularly use QEMU with KVM HV on our A-EON AmigaOne X5000 machines (book3e). It works fast and without any problems.

Screenshot tour of QEMU/KVM HV on our AmigaOnes:

- https://i.ibb.co/m4vgwNT/Kernel-6-1-rc3-Power-PC.png
- https://i.ibb.co/Fwdjf7Z/Kernel-6-0-rc6-Power-PC.png
- https://i.ibb.co/LYnJGdF/Kernel-5-19-rc5-Power-PC-2.png
- https://i.ibb.co/vz1Wm5z/QEMU-with-9p-and-USB-sound.png
- https://i.ibb.co/ScMjtp7/Kernel-5-17-alpha5-Power-PC.png
- https://i.ibb.co/LQryFcK/Kernel-5-17-alpha4-Power-PC.png
- https://i.ibb.co/kKLx9mf/Kernel-5-10-89-Power-PC.png
- https://i.ibb.co/LRG1RDV/Kernel-5-10-89-Power-PC-2.png
- https://i.ibb.co/NCFqY0k/QEMU-USB-Audio-on-Void-PPC.png
- https://i.ibb.co/N1vL5Kd/Kernel-5-16-alpha3-Power-PC.png
- https://i.ibb.co/SwjTyJk/Kernel-5-16-alpha1-Power-PC.png
- https://i.ibb.co/LkpWNPx/Kernel-5-15-rc5-Power-PC.png
- https://i.ibb.co/F8q1jDR/Kernel-5-15-rc4-Power-PC.png
- https://i.ibb.co/zZxrbhV/Kernel-5-15-alpha6-Power-PC.png
- https://i.pinimg.com/originals/a8/8b/42/a88b422870201887fc01ef44ddc1a235.png - https://i.pinimg.com/originals/57/d9/83/57d98324cd055b7ae00a87ad5a45a42f.png - https://i.pinimg.com/originals/f2/a5/e3/f2a5e34e2015381b0cb87cc51232a8bc.png - https://i.pinimg.com/originals/c5/0d/85/c50d85d7e8f20b4caa1a439faf751964.png - https://i.pinimg.com/originals/6e/3b/59/6e3b59fe10276c5644b15622a81f43f1.png

We solved some issues:

- https://forum.hyperion-entertainment.com/viewtopic.php?p=54357#p54357
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-November/236307.html
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2022-September/249021.html
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-May/229103.html
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-January/223342.html
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216379.html
- https://forum.hyperion-entertainment.com/viewtopic.php?f=58&t=4655&p=53393&hilit=KVM#p53393
- https://forum.hyperion-entertainment.com/viewtopic.php?p=53209#p53209

Please, do not remove KVM support from Book3e because it works without any problems and fast. We need it for our work.


    On 12/2/22 12:04, Daniel Henrique Barboza wrote:

        On 11/30/22 17:45, Crystal Wood wrote:

            On Mon, 2022-11-28 at 14:36 +1000, Nicholas Piggin wrote:

                BookE KVM is in a deep maintenance state, I'm not sure how much testing                 it gets. I don't have a test setup, and it does not look like QEMU has                 any HV architecture enabled. It hasn't been too painful but there are                 some cases where it causes a bit of problem not being able to test, e.g.,


                Time to begin removal process, or are there still people using it? I'm                 happy to to keep making occasional patches to try keep it going if                 there are people testing upstream. Getting HV support into QEMU would                 help with long term support, not sure how big of a job that would be.

            Not sure what you mean about QEMU not having e500 HV support?  I don't know if
            it's bitrotted, but it's there.

        AFAIK all QEMU ppc boards, aside from pSeries and the Mac ones, are always used
        emulated mode in an use case similar to what Bernhard described in his reply
        in x86 due to lack of ppc hardware).

        I am not aware of e500 KVM support in QEMU since I never attempted it. But yes,         it is present, but poorly tested - if tested at all. And the reason why there's         no push on our side to removed it from QEMU is because its code is so entwined
        with pSeries KVM that it would take too much effort.

        Do not take the presence of e500 KVM support in QEMU as a blocker to disabled
        it in
        the kernel. As far as the current QEMU usage goes e500 KVM can be removed
        too much drama from our side.

        Cedric, do you have any opinions about it?

    I can not tell how much e500 KVM is used. The last report we had
    on the topic was :


    and the last commit mentioning e500 VMs I could find is cb3778a045,
    which brings us back to QEMU 2.2 or so.

    It would be nice to 'quickly' check the state of the KVM stack on
    such boards and, may be, plan for more cleanups.




            I don't know whether anyone is still using this, but if they are, it's             probably e500mc and not e500v2 (which involved a bunch of hacks to get almost-             sorta-usable performance out of hardware not designed for virtualization).  I             do see that there have been a few recent patches on QEMU e500 (beyond the             treewide cleanup type stuff), though I don't know if they're using KVM.  CCing
            them and the QEMU list.

            I have an e6500 I could occasionally test on, if it turns out people do still
            care about this.  Don't count me as the use case, though. :-)

            FWIW, as far as the RECONCILE_IRQ_STATE issue, that used to be done in             kvmppc_handle_exit(), but was moved in commit 9bd880a2c882 to be "cleaner and
            faster". :-P


Dear all,
please, do not proceed removing KVM support to Book3e.

The PowerProgressCommunity, our not-for-profit organisation of PowerPC and alternative platforms enthusiasts is in the process of hardware testing our new “Powerboard Tyche”, a fully open hardware motherboard for a laptop based on a NXP T2080 which is a Book3e e6500 CPU (4 physical cores, 8 logical cores), see our recent blog post about it

With such a board we hope to have a new small niche group of users of a PowerPC Book3e platform that will be more than happy to keep using QEMU with KVM enabled as using VMs without KVM is way too slow.

At the moment we still have a working NXP DevKit based on the same T2080 CPU and thank to a patch submitted back in December 2021 we can use QEMU with KVM enable on it. The only issue we have so far is that it only starts when setting it as “e5500” (that does not have altivec) because starting it with e6500 (that has altivec) it does not start.

We published a blog post about QEMU with KVM enable back in December 2021, I made a screenshot with multiple QEMU instances

I am also aware of users of the A-Eon AmigaOne X5000 computers (still being produced and sold) that successfully use QEMU with KVM enabled, their system are based either on a NXP P5020 or P5040, both Book3e e5500, so without altivec.

So, again, please, do not remove KVM support to Book3e we need that!


reply via email to

[Prev in Thread] Current Thread [Next in Thread]