From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51698) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fYABB-0002OT-Cv for qemu-devel@nongnu.org; Wed, 27 Jun 2018 09:08:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fYAB7-0005wz-GK for qemu-devel@nongnu.org; Wed, 27 Jun 2018 09:08:13 -0400 Received: from mail-wr0-x241.google.com ([2a00:1450:400c:c0c::241]:33097) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fYAB7-0005vC-8r for qemu-devel@nongnu.org; Wed, 27 Jun 2018 09:08:09 -0400 Received: by mail-wr0-x241.google.com with SMTP id k16-v6so1994641wro.0 for ; Wed, 27 Jun 2018 06:08:09 -0700 (PDT) References: <20180625131253.11218-1-kraxel@redhat.com> <20180625131253.11218-2-kraxel@redhat.com> <6ad67e44-b002-1cd7-cfd1-2d98ebde1a7e@redhat.com> <20180627065126.mwzdxshr3njzok7n@sirius.home.kraxel.org> <0df8a05c-43fc-6e85-b13c-d3f5c4691964@redhat.com> <87fu18ach6.fsf_-_@dusky.pond.sub.org> <20180627085217.blrsx5lmu4sau4fd@sirius.home.kraxel.org> <20180627110912.GA2424@work-vm> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <20180627110912.GA2424@work-vm> Date: Wed, 27 Jun 2018 14:08:06 +0100 Message-ID: <87bmbwwf61.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] Drop support for 32bit hosts in qemu? (was: [PULL 1/6] audio/hda: create millisecond timers that handle IO) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: Peter Maydell , Martin Schrodt , Thomas Huth , Markus Armbruster , QEMU Developers , Max Reitz , Gerd Hoffmann Dr. David Alan Gilbert writes: > * Peter Maydell (peter.maydell@linaro.org) wrote: >> On 27 June 2018 at 09:52, 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 f= or 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 Benn=C3=A9e