On 30/01/2023 20:45, Alex Bennée wrote:
Daniel P. Berrangé <berrange@xxxxxxxxxx> 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@xxxxxxxxxx> 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.
ATB,
Mark.
