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[80.187.66.157]) by smtp.gmail.com with ESMTPSA id jh14-20020a0562141fce00b005dd8b9345b6sm4021282qvb.78.2023.04.05.01.01.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 Apr 2023 01:01:46 -0700 (PDT) Message-ID: <55cab42d-19b1-c454-8979-0aaae4a64a00@redhat.com> Date: Wed, 5 Apr 2023 10:01:42 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [RFC PATCH] docs/about/deprecated: Deprecate 32-bit host systems Content-Language: en-US To: BALATON Zoltan , =?UTF-8?Q?C=c3=a9dric_Le_Goater?= Cc: Mark Cave-Ayland , =?UTF-8?Q?Alex_Benn=c3=a9e?= , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Peter Maydell , Stefan Hajnoczi , Richard Henderson , libvir-list@redhat.com, Paolo Bonzini , Reinoud Zandijk , Ryo ONODERA , Brad Smith , Stefan Weil , qemu-devel@nongnu.org References: <20230130114428.1297295-1-thuth@redhat.com> <87h6w7694t.fsf@linaro.org> <4e42ea6b-0f9b-69e0-1593-c3288712d13c@redhat.com> <77c41865-1585-6a3a-f02e-1c072a4368bd@eik.bme.hu> From: Thomas Huth In-Reply-To: <77c41865-1585-6a3a-f02e-1c072a4368bd@eik.bme.hu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -39 X-Spam_score: -4.0 X-Spam_bar: ---- X-Spam_report: (-4.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-1.925, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 04/04/2023 17.42, BALATON Zoltan wrote: > On Tue, 4 Apr 2023, Cédric Le Goater wrote: >> [ adding Zoltan ] >> >> On 4/4/23 16:00, Thomas Huth wrote: >>> On 05/02/2023 23.12, Mark Cave-Ayland wrote: >>>> On 30/01/2023 20:45, Alex Bennée wrote: >>>> >>>>> Daniel P. Berrangé writes: >>>>> >>>>>> On Mon, Jan 30, 2023 at 11:47:02AM +0000, Peter Maydell wrote: >>>>>>> On Mon, 30 Jan 2023 at 11:44, Thomas Huth wrote: >>>>>>>> >>>>>>>> Testing 32-bit host OS support takes a lot of precious time during >>>>>>>> the QEMU >>>>>>>> contiguous integration tests, and considering that many OS vendors >>>>>>>> stopped >>>>>>>> shipping 32-bit variants of their OS distributions and most hardware >>>>>>>> from >>>>>>>> the past >10 years is capable of 64-bit >>>>>>> >>>>>>> True for x86, not necessarily true for other architectures. >>>>>>> Are you proposing to deprecate x86 32-bit, or all 32-bit? >>>>>>> I'm not entirely sure about whether we're yet at a point where >>>>>>> I'd want to deprecate-and-drop 32-bit arm host support. >>>>>> >>>>>> Do we have a feeling on which aspects of 32-bit cause us the support >>>>>> burden ? The boring stuff like compiler errors from mismatched integer >>>>>> sizes is mostly quick & easy to detect simply through a cross compile. >>>>>> >>>>>> I vaguely recall someone mentioned problems with atomic ops in the past, >>>>>> or was it 128-bit ints, caused implications for the codebase ? >>>>> >>>>> Atomic operations on > TARGET_BIT_SIZE and cputlb when >>>>> TCG_OVERSIZED_GUEST is set. Also the core TCG code and a bunch of the >>>>> backends have TARGET_LONG_BITS > TCG_TARGET_REG_BITS ifdefs peppered >>>>> throughout. >>>> >>>> I am one of an admittedly small group of people still interested in >>>> using KVM-PR on ppc32 to boot MacOS, although there is some interest on >>>> using 64-bit KVM-PR to run super-fast MacOS on modern Talos hardware. >>>> >>>>  From my perspective losing the ability to run 64-bit guests on 32-bit >>>> hardware with TCG wouldn't be an issue, as long as it were still >>>> possible to use qemu-system-ppc on 32-bit hardware using both TCG and >>>> KVM to help debug the remaining issues. >>> >>>   Hi Mark! >>> >>> Just out of curiosity (since we briefly talked about 32-bit KVM on ppc in >>> today's QEMU/KVM call - in the context of whether qemu-system-ppc64 is a >>> proper superset of qemu-system-ppc when it comes to building a unified >>> qemu-system binary): What host machine are you using for running KVM-PR? >>> And which QEMU machine are you using for running macOS? The mac99 or the >>> g3beige machine? >> >> Zoltan, what about the pegasos2 and sam460ex machines ? can they be run >> under KVM ? > > I don't know as I don't have PPC hardware to test on but theoretically they > should work. Although BookE KVM was dropped from Linux I think so sam460ex > could only work with an old kernel on a BookE host which is now rare [...] Thanks for your explanations, that indeed helps to understand the situation! But are you sure about the BookE KVM removal in the Linux kernel? ... when I look at the arch/powerpc/kvm/ folder there, I can still see some files there with "booke" in the name? Thomas