On 3/20/26 09:54, Daniel P. Berrangé wrote:
On Fri, Mar 20, 2026 at 09:45:20AM +0300, Michael Tokarev wrote:
Is it intentional that qemu does not build utilities on 32bit hosts
anymore?
Yes, per this note:
https://www.qemu.org/docs/master/about/removed-features.html#bit-host-operating-systems-removed-in-11-0
This states:
"Keeping 32-bit *host support* alive was a substantial burden for the QEMU project.
Thus QEMU dropped all support for all 32-bit host systems."
The parts of qemu which deal with running as emulator I agree with this (e.g.
removal of atomic requirements and such as you stated below).
But Michael is referring to the *tools*, like qemu-img and such.
There is no need to limit those to 64-bit hosts.
Those tools are necessary on a lot of platforms and architectures,
not just those which are officially supported by qemu.
On Debian there are quite some hard dependencies of some debian packages
on the qemu tools to build other things.
I once had a debian bug report about this (which I would need to look up again).
That said, I strongly agree with Michael that we should not
pro-active prevent building the tools on 32-bit platforms (or
other architectures) and restore the ability to build (the tools only)
on 32-bit hosts again (even without official support).
Helge
I understand system/user emulation on a 32bit host, where there are
quite some real difficulties with address space sizes.
But what's wrong with building qemu-img et al on a 32bit host? It
doesn't require 64bit address space..
While the acclerator burden was one big factor, there were other
code removals enabled by dropping 32-bit hosts, such as removal
of 64-bit atomics emulation, and removal of some back compat
definitions for 32-bit kernels, and simplifying assumptions about
CPU features in other code, all of which leak out into common
code used by qemu-img & similar tools.
Keeping an arbitrary, and continually changing, subset of QEMU
supporting 32-bit while most code dropped 64-bit would not be
fun situation for maintainers, even with CI to try to detect
problems.
With regards,
Daniel
