On Wed, Sep 15, 2021 at 10:51:56AM +0200, Philippe Mathieu-Daudé wrote: > On 9/15/21 10:37 AM, Daniel P. Berrangé wrote: > > On Wed, Sep 15, 2021 at 09:42:48AM +0200, Thomas Huth wrote: > >> On 14/09/2021 17.22, Richard Henderson wrote: > >>> On 9/14/21 5:26 AM, Peter Maydell wrote: > >>>> (2) RAM blocks should have a length that fits inside a > >>>> signed 32-bit type on 32-bit hosts (at least I assume this > >>>> is where the 2047MB limit is coming from; in theory this ought > >>>> to be improveable but auditing the code for mishandling of > >>>> RAMblock sizes to ensure we weren't accidentally stuffing > >>>> their size into a signed 'long' somewhere would be kind > >>>> of painful) > >>> > >>> Recalling that the win64 abi model is p64, i.e. 'long' is still 32-bit > >>> while pointers are 64-bit, how close do we think we are to this being > >>> fixed already? > >>> > >>>> Even if we did fix (2) we'd need to compromise on (3) > >>>> sometimes still -- if a board has 4GB of RAM that's > >>>> not going to fit in 32 bits regardless. But we would be > >>>> able to let boards with 2GB have 2GB. > >>> > >>> I'm not opposed to deprecating 32-bit hosts... ;-) > >> > >> I think we should consider this again, indeed. Plain 32-bit CPUs are quite > >> seldom these days, aren't they? And I think we urgently need to decrease > >> the > >> amount of things that we have to test and maintain in our CI and developer > >> branches... So is there still a really really compelling reason to keep > >> 32-bit host support alive? > > > > I think it probably depends on the architecture to some extent. > > > > i386 is possibly getting rare enough to consider dropping, though > > IIUC, KVM in the kernel still supports it. Would feel odd to drop > > it in QEMU if the kernel still thinks it is popular enough to keep > > KVM support. > > > > armv7 feels like it is relatively common as 64-bit didn't arrive > > in widespread use until relatively recent times compared to x86_64. > > KVM dropped armv7, but then hardware for that was never widespread, > > so armv7 was always TCG dominated > > > > Other 32-bit arches were/are always rare. > > While I could understand there are rare uses of system emulation on > 32-bit hosts, I still believe user-emulation is used, but would like > to be proven to the contrary. With that in mind, I'm not sure removing > sysemu on 32-bit hosts is worthful. Maybe we should ask distribution > maintainers first, then eventually poll the community? Or start with > a deprecation warning?
Well Debian still supports arm7, i686, mips officially, and several more unofficially, so that's an easy answer from that side. Fedora only has arm7, having dropped i686 a while ago. I don't have insight into usage of QEMU on any platforms breakdown though. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
