Re: [RFC 0/5] KVM: drop 32-bit host support on all architectures

["Arnd Bergmann" <arnd@arndb.de>]

On Fri, Dec 13, 2024, at 04:51, A. Wilcox wrote:
> On Dec 12, 2024, at 6:55 AM, Arnd Bergmann <arnd@kernel.org> wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>> 
>> I submitted a patch to remove KVM support for x86-32 hosts earlier
>> this month, but there were still concerns that this might be useful for
>> testing 32-bit host in general, as that remains supported on three other
>> architectures. I have gone through those three now and prepared similar
>> patches, as all of them seem to be equally obsolete.
>> 
>> Support for 32-bit KVM host on Arm hardware was dropped back in 2020
>> because of lack of users, despite Cortex-A7/A15/A17 based SoCs being
>> much more widely deployed than the other virtualization capable 32-bit
>> CPUs (Intel Core Duo/Silverthorne, PowerPC e300/e500/e600, MIPS P5600)
>> combined.
>
>
> I do use 32-bit KVM on a Core Duo “Yonah” and a Power Mac G4 (MDD), for
> purposes of bisecting kernel issues without having to reboot the host
> machine (when it can be duplicated in a KVM environment).
>
> I suppose it would still be possible to run the hosts on 6.12 LTS for
> some time with newer guests, but it would be unfortunate.

Would it be an option for you to just test those kernels on 64-bit
machines? I assume you prefer to do native builds on 32-bit hardware
because that fits your workflow, but once you get into debugging
in a virtual machine, the results should generally be the same when
building and running on a 64-bit host for both x86-32 and ppc32-classic,
right?

      Arnd