Re: [RFC PATCH] docs/about/deprecated: Deprecate 32-bit host systems

On Tue, 4 Apr 2023, Cédric Le Goater wrote: > [ adding Zoltan ] > > On 4/4/23 16:00, Thomas Huth wrote: >> On 05/02/2023 23.12, Mark Cave-Ayland wrote: >>> On 30/01/2023 20:45, Alex Bennée wrote: >>> >>>> Daniel P. Berrangé <berrange(a)redhat.com&gt; writes: >>>> >>>>> On Mon, Jan 30, 2023 at 11:47:02AM +0000, Peter Maydell wrote: >>>>>> On Mon, 30 Jan 2023 at 11:44, Thomas Huth <thuth(a)redhat.com&gt; wrote: >>>>>>> >>>>>>> Testing 32-bit host OS support takes a lot of precious time during >>>>>>> the QEMU >>>>>>> contiguous integration tests, and considering that many OS vendors >>>>>>> stopped >>>>>>> shipping 32-bit variants of their OS distributions and most hardware >>>>>>> from >>>>>>> the past >10 years is capable of 64-bit >>>>>> >>>>>> True for x86, not necessarily true for other architectures. >>>>>> Are you proposing to deprecate x86 32-bit, or all 32-bit? >>>>>> I'm not entirely sure about whether we're yet at a point where >>>>>> I'd want to deprecate-and-drop 32-bit arm host support. >>>>> >>>>> Do we have a feeling on which aspects of 32-bit cause us the support >>>>> burden ? The boring stuff like compiler errors from mismatched integer >>>>> sizes is mostly quick & easy to detect simply through a cross compile. >>>>> >>>>> I vaguely recall someone mentioned problems with atomic ops in the past, >>>>> or was it 128-bit ints, caused implications for the codebase ? >>>> >>>> Atomic operations on > TARGET_BIT_SIZE and cputlb when >>>> TCG_OVERSIZED_GUEST is set. Also the core TCG code and a bunch of the >>>> backends have TARGET_LONG_BITS > TCG_TARGET_REG_BITS ifdefs peppered >>>> throughout. >>> >>> I am one of an admittedly small group of people still interested in >>> using KVM-PR on ppc32 to boot MacOS, although there is some interest on >>> using 64-bit KVM-PR to run super-fast MacOS on modern Talos hardware. >>> >>>  From my perspective losing the ability to run 64-bit guests on 32-bit >>> hardware with TCG wouldn't be an issue, as long as it were still >>> possible to use qemu-system-ppc on 32-bit hardware using both TCG and >>> KVM to help debug the remaining issues. >> >>   Hi Mark! >> >> Just out of curiosity (since we briefly talked about 32-bit KVM on ppc in >> today's QEMU/KVM call - in the context of whether qemu-system-ppc64 is a >> proper superset of qemu-system-ppc when it comes to building a unified >> qemu-system binary): What host machine are you using for running KVM-PR? >> And which QEMU machine are you using for running macOS? The mac99 or the >> g3beige machine? > > Zoltan, what about the pegasos2 and sam460ex machines ? can they be run > under KVM ? I don't know as I don't have PPC hardware to test on but theoretically they should work. Although BookE KVM was dropped from Linux I think so sam460ex could only work with an old kernel on a BookE host which is now rare