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

["Alex Bennée" <alex.bennee@linaro.org>]

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 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.

>
> With regards,
> Daniel


-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro