On 12/13/24 09:03, Arnd Bergmann wrote:

On Fri, Dec 13, 2024, at 04:51, A. Wilcox wrote:

quoted

On Dec 12, 2024, at 6:55 AM, Arnd Bergmann [off-list ref] wrote:

quoted

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?

Certainly for x86-32; ppc32 should be able to use PR-state (aka trap and 
emulate) KVM on a 64-bit host but it's a bit more picky.  Another 
possibility for ppc32 is just emulation with QEMU.

Paolo