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[92.176.132.141]) by smtp.gmail.com with ESMTPSA id h11-20020a1ccc0b000000b003fa8158135esm7901577wmb.11.2023.06.26.03.06.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Jun 2023 03:06:05 -0700 (PDT) Message-ID: <39a174a0-a64d-c687-52da-40aeb7179de0@linaro.org> Date: Mon, 26 Jun 2023 12:06:03 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v2 0/3] target/i386: allow using named CPU modeles with user mode emulation Content-Language: en-US To: Paolo Bonzini , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= Cc: qemu-devel@nongnu.org References: <20230626083317.144746-1-pbonzini@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=2a00:1450:4864:20::32a; envelope-from=richard.henderson@linaro.org; helo=mail-wm1-x32a.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=-0.089, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 6/26/23 11:37, Paolo Bonzini wrote: > On Mon, Jun 26, 2023 at 11:36 AM Daniel P. Berrangé wrote: >>>> If someone wants Nehalem then they should be using qemu-x86_64. >>>> If someone wants qemu-i386 then they should be using an older >>>> named CPU model predating 'lm'. >>> >>> What you write is true for qemu-system-*, but the problem is that >>> qemu-user binaries are only able to run one ELF target. qemu-x86_64 is >>> not able to run i386 binaries, unlike a 64-bit kernel; and that's >>> really intrinsic in the design of qemu-user because implementing >>> multiple ABIs (including multiple definitions of structs and syscall >>> numbers) would require compiling the same files multiple times. >> >> Oh, right, yes, ignore my comment. > > By the way it's possible that the above comment would not be true > anymore with the "one binary" work that is going on (though I'm not > sure if that applies to system emulation only). However, the effect on > speed for 32-bit hosts remains true until we ditch them altogether. Yes, one binary work is system-mode only. Primarily because of the ABI issues you describe. r~