From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52136) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fYACg-0003nq-Ah for qemu-devel@nongnu.org; Wed, 27 Jun 2018 09:09:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fYACa-0007cz-KE for qemu-devel@nongnu.org; Wed, 27 Jun 2018 09:09:46 -0400 Received: from mail-wm0-x243.google.com ([2a00:1450:400c:c09::243]:39770) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fYACa-0007c9-3l for qemu-devel@nongnu.org; Wed, 27 Jun 2018 09:09:40 -0400 Received: by mail-wm0-x243.google.com with SMTP id p11-v6so5413261wmc.4 for ; Wed, 27 Jun 2018 06:09:40 -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> <87bmbwwf61.fsf@linaro.org> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <87bmbwwf61.fsf@linaro.org> Date: Wed, 27 Jun 2018 14:09:37 +0100 Message-ID: <87a7rgwf3i.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 Alex Benn=C3=A9e writes: > 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 = for some >>> >> embedded systems/SoCs 32bit might still be common and QEMU useful fo= r 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. I should point out that is what TCG_OVERSIZED_GUEST is defined for. -- Alex Benn=C3=A9e