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[109.43.177.75]) by smtp.gmail.com with ESMTPSA id d10-20020a05600c3aca00b003eb369abd92sm10529537wms.2.2023.02.27.23.52.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Feb 2023 23:52:50 -0800 (PST) Message-ID: <697e536d-eb65-32d9-279f-b2e6ab5e718a@redhat.com> Date: Tue, 28 Feb 2023 08:52:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [PATCH 1/2] docs/about: Deprecate 32-bit x86 hosts and qemu-system-i386 Content-Language: en-US To: Richard Henderson , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= Cc: qemu-devel@nongnu.org, Peter Maydell , Paolo Bonzini , Markus Armbruster , =?UTF-8?Q?Alex_Benn=c3=a9e?= , qemu-arm@nongnu.org, Maxim Levitsky , libvir-list@redhat.com, xen-devel@lists.xenproject.org, Reinoud Zandijk , "Michael S . Tsirkin" , Marcel Apfelbaum References: <20230227111050.54083-1-thuth@redhat.com> <20230227111050.54083-2-thuth@redhat.com> From: Thomas Huth In-Reply-To: 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: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 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=-0.089, 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 27/02/2023 21.25, Richard Henderson wrote: > On 2/27/23 01:50, Daniel P. Berrangé wrote: >> On Mon, Feb 27, 2023 at 12:10:49PM +0100, Thomas Huth wrote: >>> Hardly anybody still uses 32-bit x86 hosts today, so we should >>> start deprecating them to finally have less test efforts. >>> With regards to 32-bit KVM support in the x86 Linux kernel, >>> the developers confirmed that they do not need a recent >>> qemu-system-i386 binary here: >>> >>>   https://lore.kernel.org/kvm/Y%2ffkTs5ajFy0hP1U@google.com/ >>> >>> Signed-off-by: Thomas Huth >>> --- >>>   docs/about/deprecated.rst | 13 +++++++++++++ >>>   1 file changed, 13 insertions(+) >>> >>> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst >>> index 15084f7bea..98517f5187 100644 >>> --- a/docs/about/deprecated.rst >>> +++ b/docs/about/deprecated.rst >>> @@ -196,6 +196,19 @@ CI coverage support may bitrot away before the >>> deprecation process >>>   completes. The little endian variants of MIPS (both 32 and 64 bit) are >>>   still a supported host architecture. >>> +32-bit x86 hosts and ``qemu-system-i386`` (since 8.0) >>> +''''''''''''''''''''''''''''''''''''''''''''''''''''' >>> + >>> +Testing 32-bit x86 host OS support takes a lot of precious time during the >>> +QEMU contiguous integration tests, and considering that most OS vendors >>> +stopped shipping 32-bit variants of their x86 OS distributions and most >>> +x86 hardware from the past >10 years is capable of 64-bit, keeping the >>> +32-bit support alive is an inadequate burden for the QEMU project. Thus >>> +QEMU will soon drop the support for 32-bit x86 host systems and the >>> +``qemu-system-i386`` binary. Use ``qemu-system-x86_64`` (which is a proper >>> +superset of ``qemu-system-i386``) on a 64-bit host machine instead. >> >> I feel like we should have separate deprecation entries for the >> i686 host support, and for qemu-system-i386 emulator binary, as >> although they're related they are independant features with >> differing impact. > > Agreed. OK, fair, I'll rework my patch according to your suggestion, Daniel. >> 32-bit x86 hosts >> '''''''''''''''' >> >> Support for 32-bit x86 host deployments is increasingly uncommon in >> mainstream Linux distributions given the widespread availability of >> 64-bit x86 hardware. The QEMU project no longer considers 32-bit >> x86 support to be an effective use of its limited resources, and >> thus intends to discontinue it. >> >> Current users of QEMU on 32-bit x86 hosts should either continue >> using existing releases of QEMU, with the caveat that they will >> no longer get security fixes, or migrate to a 64-bit platform >> which remains capable of running 32-bit guests if needed. > Ack. > >> >> ``qemu-system-i386`` binary removal >> ''''''''''''''''''''''''''''''''''' >> >> The ``qemu-system-x86_64`` binary can be used to run 32-bit guests >> by selecting a 32-bit CPU model, including KVM support on x86_64 >> hosts. Once support for the 32-bit x86 host platform is discontinued, >> the ``qemu-system-i386`` binary will be redundant. > > Missing "kvm" in this last sentence?  It is otherwise untrue for tcg. I assume that Daniel only thought of 32-bit x86 hosts here, but indeed, it's untrue for non-x86 32-bit hosts. So this really should refer to KVM on 32-bit x86 hosts instead. I'll rephrase it in v2. Thomas