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Tsirkin" Cc: Daniel P. =?utf-8?Q?Berrang=C3=A9?= , Thomas Huth , Peter Maydell , libvir-list@redhat.com, Richard Henderson , qemu-devel@nongnu.org, qemu-arm@nongnu.org, Reinoud Zandijk , Marcel Apfelbaum , xen-devel@lists.xenproject.org, Paolo Bonzini , Maxim Levitsky , Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [PATCH 1/2] docs/about: Deprecate 32-bit x86 hosts and qemu-system-i386 References: <20230227111050.54083-1-thuth@redhat.com> <20230227111050.54083-2-thuth@redhat.com> <20230227150858-mutt-send-email-mst@kernel.org> <84d7d3e5-0da2-7506-44a7-047ebfcfc4da@redhat.com> <20230228031026-mutt-send-email-mst@kernel.org> <20230228040115-mutt-send-email-mst@kernel.org> <20230228050908-mutt-send-email-mst@kernel.org> Date: Tue, 28 Feb 2023 11:39:39 +0100 In-Reply-To: <20230228050908-mutt-send-email-mst@kernel.org> (Michael S. Tsirkin's message of "Tue, 28 Feb 2023 05:11:20 -0500") Message-ID: <87cz5uhy50.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-TUID: 7WjkKaWLCtid "Michael S. Tsirkin" writes: > On Tue, Feb 28, 2023 at 09:40:49AM +0000, Daniel P. Berrang=C3=A9 wrote: >> On Tue, Feb 28, 2023 at 10:14:52AM +0100, Thomas Huth wrote: >> > On 28/02/2023 10.03, Michael S. Tsirkin wrote: >> > > On Tue, Feb 28, 2023 at 08:59:52AM +0000, Daniel P. Berrang=C3=A9 wr= ote: >> > > > On Tue, Feb 28, 2023 at 03:19:20AM -0500, Michael S. Tsirkin wrote: >> > > > > On Tue, Feb 28, 2023 at 08:49:09AM +0100, Thomas Huth wrote: >> > > > > > On 27/02/2023 21.12, Michael S. Tsirkin wrote: >> > > > > > > On Mon, Feb 27, 2023 at 11:50:07AM +0000, Daniel P. Berrang= =C3=A9 wrote: >> > > > > > > > I feel like we should have separate deprecation entries fo= r the >> > > > > > > > i686 host support, and for qemu-system-i386 emulator binar= y, as >> > > > > > > > although they're related they are independant features with >> > > > > > > > differing impact. eg removing qemu-system-i386 affects all >> > > > > > > > host architectures, not merely 32-bit x86 host, so I think= we >> > > > > > > > can explain the impact more clearly if we separate them. >> > > > > > >=20 >> > > > > > > Removing qemu-system-i386 seems ok to me - I think qemu-syst= em-x86_64 is >> > > > > > > a superset. >> > > > > > >=20 >> > > > > > > Removing support for building on 32 bit systems seems like a= pity - it's >> > > > > > > one of a small number of ways to run 64 bit binaries on 32 b= it systems, >> > > > > > > and the maintainance overhead is quite small. >> > > > > >=20 >> > > > > > Note: We're talking about 32-bit *x86* hosts here. Do you real= ly think that >> > > > > > someone is still using QEMU usermode emulation >> > > > > > to run 64-bit binaries on a 32-bit x86 host?? ... If so, I'd b= e very surprised! >> > > > >=20 >> > > > > I don't know - why x86 specifically? One can build a 32 bit bina= ry on any host. >> > > > > I think 32 bit x86 environments are just more common in the clou= d. >> > > >=20 >> > > > Can you point to anything that backs up that assertion. Clouds I've >> > > > seen always give you a 64-bit environment, and many OS no longer >> > > > even ship 32-bit installable media. >> > >=20 >> > > Sorry about being unclear. I meant that it seems easier to run CI in= the >> > > cloud in a 32 bit x64 environment than get a 32 bit ARM environment. >> >=20 >> > It's still doable ... but for how much longer? We're currently dependi= ng on >> > Fedora, but they also slowly drop more and more support for this >> > environment, see e.g.: >>=20 >> FWIW, we should cull our fedora-i386-cross.docker dockerfile and >> replace it with a debian i686 dockerfile generated by lcitool. >> There's no compelling reason why i686 should be different from >> all our other cross builds which are based on Debian. The Debian >> lcitool generated container would have access to a wider range >> of deps than our hand written Fedora one. >>=20 >> > https://www.theregister.com/2022/03/10/fedora_inches_closer_to_droppi= ng/ >>=20 >> With regards, >> Daniel > > ... and is closer to where 32 bit is likely to be deployed which is > systems like e.g. raspberry pi os which until recently was only > 32 bit. 32 bit ARM. How is that an argument for continued maintenance of 32 bit x86? If the argument goes like "32 bit x86 is easier to test in CI", then I don't buy it. Testing 64 bit ARM + 32 bit x86 does not magically replace testing 32 bit ARM. The question to answer: Is 32 bit x86 worth its upkeep? Two sub-questions: 1. Is it worth the human attention? 2. Is it worth (scarce!) CI minutes? I want to see an argument for benefits justifying the costs. A benefit like "somebody out there might still want to use it" I'd value at zero.