Re: [Qemu-devel] Drop support for 32bit hosts in qemu? (was: [PULL 1/6] audio/hda: create millisecond timers that handle IO)

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

Dr. David Alan Gilbert <dgilbert@redhat.com> writes:

> * Peter Maydell (peter.maydell@linaro.org) wrote:
>> On 27 June 2018 at 09:52, Gerd Hoffmann <kraxel@redhat.com> wrote:
>> >   Hi,
>> >
>> >> > Is QEMU still useful on 32-bit hosts?  Honest question!
>> >>
>> >> I guess it depends on what 32-bit hosts you consider. If you look at only
>> >> x86 vs. x86_64 then probably x86 is not that important any more but for some
>> >> embedded systems/SoCs 32bit might still be common and QEMU useful for those
>> >> (also as host not only emulated).
>>
>> I would generally agree with this. For x86 32-bit is probably
>> droppable, but for non-x86 the situation is much less clear.
>>
>> > Well.  I've used kvm with an 32bit arm soc (cubietruck).  It's very
>> > slow.  And all the arm architecture improvements to support kvm better
>> > are for aarch64 only.
>>
>> Cubietruck (a Cortex-A7) is a pretty slow 32-bit Arm core.
>>
>> Ask again in a couple of years :-)
>
> How about dropping support for 32 bit hosts that don't have
> 64bit atomics?
> That should be a much smaller set.

Seems a bit harsh - we don't support MTTCG if you don't have big enough
atomics, but we don't drop TCG support completely. And in fact in the
case in point I don't think you could trigger a bug with emulation being
single threaded and all.

>
> Dave
>
>> thanks
>> -- PMM
>>


--
Alex Bennée