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From: | Thomas Huth |
Subject: | Re: [RFC PATCH] docs/about/deprecated: Deprecate 32-bit host systems |
Date: | Tue, 4 Apr 2023 16:00:10 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 |
On 05/02/2023 23.12, Mark Cave-Ayland wrote:
On 30/01/2023 20:45, Alex Bennée wrote:Daniel P. Berrangé <berrange@redhat.com> 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@redhat.com> wrote:Testing 32-bit host OS support takes a lot of precious time during the QEMUcontiguous 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-bitTrue 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?
Unrelated to KVM: Do you happen to know whether there are any problems when running 32-bit guests with TCG with the mac99 or g3beige machine while using qemu-system-ppc64 ?
Thanks, Thomas
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