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[173.197.98.118]) by smtp.gmail.com with ESMTPSA id y10-20020a17090322ca00b001947c22185bsm8135457plg.184.2023.01.30.11.19.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Jan 2023 11:19:40 -0800 (PST) Message-ID: <9c529b2a-14bd-fd50-c0d9-87f2253ee0bb@linaro.org> Date: Mon, 30 Jan 2023 09:19:36 -1000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [RFC PATCH] docs/about/deprecated: Deprecate 32-bit host systems Content-Language: en-US To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Peter Maydell Cc: Thomas Huth , qemu-devel@nongnu.org, Stefan Hajnoczi , libvir-list@redhat.com, Paolo Bonzini , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Reinoud Zandijk , Ryo ONODERA , Brad Smith , Stefan Weil References: <20230130114428.1297295-1-thuth@redhat.com> From: Richard Henderson In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::62e; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x62e.google.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.09, RCVD_IN_DNSWL_NONE=-0.0001, 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 1/30/23 02:01, Daniel P. Berrangé wrote: > I vaguely recall someone mentioned problems with atomic ops in the past, > or was it 128-bit ints, caused implications for the codebase ? TCG_OVERSIZED_GUEST, where 32-bit host running 64-bit guest cannot run the guest except in round-robin mode. It's not *that* much of a support burden, since we're not going to eliminate round-robin mode. But I do question whether we need to support 64-bit guests on 32-bit hosts at all. Retaining 32-bit on 32-bit allows arm32 to emulate i686, which I suspect, but have no proof, is the limit of what users actually want. r~