Earlier this month, a patch dropped support for 32-bit x86KVM hosts as part of a patch to clean up x86 32-bit kernel code for x86_64 systems. Now, the patch has been spun off into its own patch series, while also raising the prospect of ending 32-bit KVM host support on all CPU architectures, not just x86 changes.

Work continues to clean up the x86 kernel code on x86_64 hardware, and a separate patch has now been branched out to end 32-bit KVM host support on all architectures. 32-bit KVM guest support will remain, these patches are just to end support for 32-bit virtualization hosts... after all, who will be running leading upstream kernels in a 32-bit environment and doing any virtualization hosting in production in 2025+?

Not only does it drop 32-bit KVM host support for x86, the patch also ends support for PowerPC, MIPS, and RISC-V. 32-bit ARM dropped support for KVM hosts several years ago.

ArndBergmann states in the patch series [RFC0/5] KVM: Drop 32-bit host support on all architectures:

"I submitted a patch earlier this month to remove KVM support for x86-32 hosts, but there was still concern that this might help test 32-bit hosts, since 32-bit hosts are still supported on the other three architectures. I have now checked all three architectures and prepared a similar patch, as they all seem to be equally out of date.

Although Cortex-A7/A15/A17-based SoCs are more widely deployed than other virtualization-capable 32-bit CPUs (Intel Core Duo/Silverthorne, PowerPCe300/e500/e600, MIPSP5600), support for 32-bit KVM hosts on Arm hardware was dropped as early as 2020 due to a lack of users.

If there are no real users left (excluding regression testing that the developers may be doing), it might be reasonable to abandon all of them at the same time. Please let me know if you are still using these machines or think they need to go through the deprecation phase first. "

So if you're still using a Linux 32-bit system as a kernel-based virtual machine (KVM) host, now is the time to let everyone know and debate whether it should remain in the mainline Linux kernel... especially if using existing Linux LTS versions is not feasible, such as the recently launched Linux 6.12 LTS.

Let’s wait and see what happens with these patches, and perhaps 2025 will end support for 32-bit KVM hosts forever.