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Wed, 29 Jan 2025 04:47:33 -0800 (PST) X-Google-Smtp-Source: AGHT+IGp5b+BLCJjHjmqADg5/Ea8KEgaErytnUi109qNHUS2qL53o/ntwe49UF/OMykm1C0wlXV0bg== X-Received: by 2002:a5d:584e:0:b0:38a:8b00:6908 with SMTP id ffacd0b85a97d-38c520b0b23mr2878128f8f.54.1738154853316; Wed, 29 Jan 2025 04:47:33 -0800 (PST) Received: from [192.168.10.3] ([151.62.97.55]) by smtp.googlemail.com with ESMTPSA id ffacd0b85a97d-38c2a17d6b2sm17394260f8f.34.2025.01.29.04.47.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Jan 2025 04:47:32 -0800 (PST) Message-ID: <8a54600c-ff3f-42dd-b164-62a57de867df@redhat.com> Date: Wed, 29 Jan 2025 13:47:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/1] meson: Deprecate 32-bit host systems To: Peter Maydell , Thomas Huth Cc: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , =?UTF-8?Q?Alex_Benn=C3=A9e?= , Richard Henderson , qemu-devel@nongnu.org, stefanha@redhat.com, mark.cave-ayland@ilande.co.uk, Liviu Ionescu References: <20250128004254.33442-1-richard.henderson@linaro.org> <9a280789-9248-4eca-b50c-048fc58e3f53@redhat.com> <87plk72tvr.fsf@draig.linaro.org> <8c0eea44-d0bf-4b86-9b1b-1c2082ab2df9@linaro.org> <9bf6d4b0-7a89-4110-a1e1-46bbdb2fc793@linaro.org> From: Paolo Bonzini Content-Language: en-US Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.3, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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 1/29/25 13:23, Peter Maydell wrote: > I'm not really strongly opposed to dropping 32-bit host support, > but I don't think a thread on qemu-devel is exactly likely to > get the attention of the people who might be using this > functionality. (You could argue that functionality without > representation among the developer community is fair game > for being dumped even if it has users, of course.) On the other hand, broken tests that no one even runs among the developers are not particularly significant. It's not surprising that tests do not pass the first time and need a little tweaking when trying them on a new platform. There are many examples of parts of QEMU that stayed unmaintained for years, working relatively well for limited use cases, and were only later revamped. Most of those that I can remember are guest side: the TCG frontend for x86, ESP emulation in hw/scsi, VGA. In fact VGA still has a good number of emulation deficiencies and it's deprecated for virtualization use, but no one in their right mind would suggest slating it for removal. The difference with TCG of course is that TCG is in active development, and therefore its 32-bit host support is not surviving passively in the same way that a random device is. Still, I think we can identify at least three different parts that should be treated differently: 64-on-32, 32-on-32 system-mode emulation and 32-on-32 user-mode emulation. We could and should remove 64-on-32, maybe even without a deprecation period, but the rest I'm not so sure. I don't know enough to understand their maintenance cost (other than the mere existence of the 32-bit TCG backends), but it's certainly not comparable to 64-on-32. Paolo