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

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Laurent Vivier (laurent@vivier.eu) wrote:
> Le 27/06/2018 à 15:33, Philippe Mathieu-Daudé a écrit :
> > On 06/27/2018 06:09 AM, Thomas Huth wrote:
> >> On 27.06.2018 10:52, Gerd Hoffmann 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).
> >>>
> >>> 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.
> >>>
> >>>> Another option might be to not support audio/hda on 32bit hosts. It's not
> >>>> nice either but a lot nicer than dropping support for 32bit hosts
> >>>> alltogether to fix a problem in device emulation.
> >>>
> >>> But it also is not useful and a waste of resources to maintain 32bit
> >>> host compatibility if nobody actually uses that ...
> >>>
> >>> For me testbuilds are the only reason to compile qemu for 32bit hosts.
> >>> Since years.
> >>
> >> Well, while that's true for you, me and likely most of us developers,
> >> you can not know whether this is also true for all users of qemu. Thus
> >> this needs to be announced first for a couple of releases so that people
> >> have a chance to speak up whether they still need this or not. As
> >> mentioned earlier, embedded devices are often still 32-bit and I know
> >> that there really are people who use QEMU on embedded devices.
> >>
> >> But I think we could at least announce now already that we intend to
> >> drop support for 32-bit hosts in the future (maybe not in 2 releases
> >> already, but, let's say in 2020? 2020 is already the EOL of Python 2, so
> >> that will rule out a bunch of other legacy hosts, too).
> > 
> > linux-user is certainly widely used on ARMv6 / ARMv7.
> > 
> > Known user cases:
> > 
> > - run ARMv7 binaries on ARMv6
> > - run armhf binaries on armel
> > - run x86-64 binaries on ARMv7
> > 
> 
> I run i386 binaries on ARMv6.

Do you know if that model has the 64bit atomics (ldrexd/strexd)?

Dave

> I use it to run i386 printer driver on my raspberry Pi B+.
> Brother doesn't provide the binary for ARM, neither the source.
> 
> Thanks,
> Laurent
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK