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Wed, 17 Jul 2019 12:07:12 +0200 To: John Paul Adrian Glaubitz References: <20190714134028.315-1-laurent@vivier.eu> <20190714134028.315-2-laurent@vivier.eu> <1F76A574-2A97-4070-8EE0-0EE83A4241E9@physik.fu-berlin.de> From: Laurent Vivier Openpgp: preference=signencrypt Autocrypt: addr=laurent@vivier.eu; prefer-encrypt=mutual; keydata= mQINBFYFJhkBEAC2me7w2+RizYOKZM+vZCx69GTewOwqzHrrHSG07MUAxJ6AY29/+HYf6EY2 WoeuLWDmXE7A3oJoIsRecD6BXHTb0OYS20lS608anr3B0xn5g0BX7es9Mw+hV/pL+63EOCVm SUVTEQwbGQN62guOKnJJJfphbbv82glIC/Ei4Ky8BwZkUuXd7d5NFJKC9/GDrbWdj75cDNQx UZ9XXbXEKY9MHX83Uy7JFoiFDMOVHn55HnncflUncO0zDzY7CxFeQFwYRbsCXOUL9yBtqLer Ky8/yjBskIlNrp0uQSt9LMoMsdSjYLYhvk1StsNPg74+s4u0Q6z45+l8RAsgLw5OLtTa+ePM JyS7OIGNYxAX6eZk1+91a6tnqfyPcMbduxyBaYXn94HUG162BeuyBkbNoIDkB7pCByed1A7q q9/FbuTDwgVGVLYthYSfTtN0Y60OgNkWCMtFwKxRaXt1WFA5ceqinN/XkgA+vf2Ch72zBkJL RBIhfOPFv5f2Hkkj0MvsUXpOWaOjatiu0fpPo6Hw14UEpywke1zN4NKubApQOlNKZZC4hu6/ 8pv2t4HRi7s0K88jQYBRPObjrN5+owtI51xMaYzvPitHQ2053LmgsOdN9EKOqZeHAYG2SmRW LOxYWKX14YkZI5j/TXfKlTpwSMvXho+efN4kgFvFmP6WT+tPnwARAQABtCJMYXVyZW50IFZp dmllciA8bGF1cmVudEB2aXZpZXIuZXU+iQI4BBMBAgAiBQJWBTDeAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAAKCRDzDDi9Py++PCEdD/oD8LD5UWxhQrMQCsUgLlXCSM7sxGLkwmmF ozqSSljEGRhffxZvO35wMFcdX9Z0QOabVoFTKrT04YmvbjsErh/dP5zeM/4EhUByeOS7s6Yl HubMXVQTkak9Wa9Eq6irYC6L41QNzz/oTwNEqL1weV1+XC3TNnht9B76lIaELyrJvRfgsp9M rE+PzGPo5h7QHWdL/Cmu8yOtPLa8Y6l/ywEJ040IoiAUfzRoaJs2csMXf0eU6gVBhCJ4bs91 jtWTXhkzdl4tdV+NOwj3j0ukPy+RjqeL2Ej+bomnPTOW8nAZ32dapmu7Fj7VApuQO/BSIHyO NkowMMjB46yohEepJaJZkcgseaus0x960c4ua/SUm/Nm6vioRsxyUmWd2nG0m089pp8LPopq WfAk1l4GciiMepp1Cxn7cnn1kmG6fhzedXZ/8FzsKjvx/aVeZwoEmucA42uGJ3Vk9TiVdZes lqMITkHqDIpHjC79xzlWkXOsDbA2UY/P18AtgJEZQPXbcrRBtdSifCuXdDfHvI+3exIdTpvj BfbgZAar8x+lcsQBugvktlQWPfAXZu4Shobi3/mDYMEDOE92dnNRD2ChNXg2IuvAL4OW40wh gXlkHC1ZgToNGoYVvGcZFug1NI+vCeCFchX+L3bXyLMg3rAfWMFPAZLzn42plIDMsBs+x2yP +bkCDQRWBSYZARAAvFJBFuX9A6eayxUPFaEczlMbGXugs0mazbOYGlyaWsiyfyc3PStHLFPj rSTaeJpPCjBJErwpZUN4BbpkBpaJiMuVO6egrC8Xy8/cnJakHPR2JPEvmj7Gm/L9DphTcE15 92rxXLesWzGBbuYxKsj8LEnrrvLyi3kNW6B5LY3Id+ZmU8YTQ2zLuGV5tLiWKKxc6s3eMXNq wrJTCzdVd6ThXrmUfAHbcFXOycUyf9vD+s+WKpcZzCXwKgm7x1LKsJx3UhuzT8ier1L363RW ZaJBZ9CTPiu8R5NCSn9V+BnrP3wlFbtLqXp6imGhazT9nJF86b5BVKpF8Vl3F0/Y+UZ4gUwL d9cmDKBcmQU/JaRUSWvvolNu1IewZZu3rFSVgcpdaj7F/1aC0t5vLdx9KQRyEAKvEOtCmP4m 38kU/6r33t3JuTJnkigda4+Sfu5kYGsogeYG6dNyjX5wpK5GJIJikEhdkwcLM+BUOOTi+I9u tX03BGSZo7FW/J7S9y0l5a8nooDs2gBRGmUgYKqQJHCDQyYut+hmcr+BGpUn9/pp2FTWijrP inb/Pc96YDQLQA1q2AeAFv3Rx3XoBTGl0RCY4KZ02c0kX/dm3eKfMX40XMegzlXCrqtzUk+N 8LeipEsnOoAQcEONAWWo1HcgUIgCjhJhBEF0AcELOQzitbJGG5UAEQEAAYkCHwQYAQIACQUC VgUmGQIbDAAKCRDzDDi9Py++PCD3D/9VCtydWDdOyMTJvEMRQGbx0GacqpydMEWbE3kUW0ha US5jz5gyJZHKR3wuf1En/3z+CEAEfP1M3xNGjZvpaKZXrgWaVWfXtGLoWAVTfE231NMQKGoB w2Dzx5ivIqxikXB6AanBSVpRpoaHWb06tPNxDL6SVV9lZpUn03DSR6gZEZvyPheNWkvz7bE6 FcqszV/PNvwm0C5Ju7NlJA8PBAQjkIorGnvN/vonbVh5GsRbhYPOc/JVwNNr63P76rZL8Gk/ hb3xtcIEi5CCzab45+URG/lzc6OV2nTj9Lg0SNcRhFZ2ILE3txrmI+aXmAu26+EkxLLfqCVT ohb2SffQha5KgGlOSBXustQSGH0yzzZVZb+HZPEvx6d/HjQ+t9sO1bCpEgPdZjyMuuMp9N1H ctbwGdQM2Qb5zgXO+8ZSzwC+6rHHIdtcB8PH2j+Nd88dVGYlWFKZ36ELeZxD7iJflsE8E8yg OpKgu3nD0ahBDqANU/ZmNNarBJEwvM2vfusmNnWm3QMIwxNuJghRyuFfx694Im1js0ZY3LEU JGSHFG4ZynA+ZFUPA6Xf0wHeJOxGKCGIyeKORsteIqgnkINW9fnKJw2pgk8qHkwVc3Vu+wGS ZiJK0xFusPQehjWTHn9WjMG1zvQ5TQQHxau/2FkP45+nRPco6vVFQe8JmgtRF8WFJA== Message-ID: <13f6aa89-e3f3-61e8-fa05-cde20b55daa0@vivier.eu> Date: Wed, 17 Jul 2019 12:07:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <1F76A574-2A97-4070-8EE0-0EE83A4241E9@physik.fu-berlin.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:O8Cvytf3g0vZA+dwlWXhprxFtyt/lTjG3BkaS4yMGEZi24HX6/b mUaK38Jl8yAv/4XsFyIc4ucmgSD5b2L8UfmP64wdojYYONcNs/WS8ji/0djWAYYs+3OjL+L O5cXe16xroVbAQ8do+C4r7gP7pm3YgblgRsiRCDiAKtzJK3gwhvbxWpU7Znb2aKUksgIkbs AYEk9ImLtvc1grZdF8Dpw== X-UI-Out-Filterresults: notjunk:1;V03:K0:yjumI6c0Gjo=:UJina9qYHjOE7aJ7O9VIRl aFU7bWu8aZZZG4aUF7FqDJD97BMIJCWWNpVEO2LHyks1R+p1rNhqeC27fVvoBp8aY3f5zhYWm aOvEs/7L75xN00ODDxrjtqTO7Wddqn/myJvFiMIxPdHbU0qWPffFUMI2mQZYR572MTG2U5k7u xfxkjcmnzWrH/ocnhZD6+wUc6EKSoWs/m9IVo1ukRS8RV4lAGa5apCAH0NkPNIzWKCHzxg1C2 luXaHuKQ7tKN0tmj5Gh0A+gZcD1L/ajTgAFhjEMYwPf2MlnS8LBd3+lQzW3bonFGrtMeIsR9k hTv5Ftm6eju+YdiiLPch6c7ZAHr1v9lZGTbSQzZqWqT0BqUKTp+wQQKw24202WWceb//39vlb +lZAw8UCZSPNeAWMM795smYpBb37GJaSS0ZhvipzGbBjLzCPf8yOrMnw1TRdyfBRc8Nl5+21E 28w4eszwZttFjlfD7OexRWqioG773AdcPpHNMjJBs9WyyVZVXUCqRataTV3TQfDxWhl1Ld6sW inyZ+awQCWljLHazUrqDOtldn4jC/MPOtN1xHjqJdj97adsite1KYy34caa6sjRVrwfeIXpkI H7UT7jZVZbkflYw9469oLxQcXjdXBDQixSzD1flnNEc0/0Ao0TGRb6gHNbz//E5zWrC4bKb/r Bep+oqv+GSwJyPZX82bmYG4eAnNWpyb1UWaLwQc6+/ZboScmhng12zmfKGKM+//lSmWjW/sL3 V8erBcNpwvr5zC+lbrQzmZ3zD706NqWUx60RJ+TEaePYsbJnRXXVkgj5u4I= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 212.227.126.133 Subject: Re: [Qemu-devel] [PATCH 2/2] linux-user: manage binfmt-misc preserve-arg[0] flag X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Riku Voipio , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Le 14/07/2019 à 18:19, John Paul Adrian Glaubitz a écrit : > Hi! > >> On Jul 14, 2019, at 3:40 PM, Laurent Vivier wrote: >> >> Add --preserve-arg0 in qemu-binfmt-conf.sh to configure the preserve-arg0 >> flag. >> >> Now, if QEMU is started with -0 or QEMU_ARGV0 and an empty parameter >> argv[0] (the full pathname provided by binfmt-misc) is removed and >> replaced by argv[1] (the original argv[0] provided by binfmt-misc when >> 'P'/preserve-arg[0] is set) >> >> For instance: >> >> $ sudo QEMU_ARGV0= chroot m68k-chroot sh -c 'echo $0' >> sh >> >> without this patch: >> >> $ sudo chroot m68k-chroot sh -c 'echo $0' >> /usr/bin/sh > > As a regular user of qemu-user (we’re using qemu-user to run Debian’s buildds for m68k and sh4), I would like to add that the idea of having to pass additional environment variables to make qemu behave as expected, i.e. as the real hardware, is sub-optimal. > > I would prefer that enabling the preserve flag with the qemu-binfmt.sh script would make qemu-user behave correctly. QEMU is not able to detect if it has been started by binfmt_misc with the preserve-arg[0] enabled or not, so it can't adapt the args analysis to get the correct list. > > If I understand correctly, the current design with the environment variable was chosen because my preferred approach would break compatibility in certain cases. However, I think that correct emulation is more important than compatibility to an old broken behavior and I would therefore be in favor to make the correct behavior default. > > This will also be necessary when using qemu-user with Debian’s sbuild to “cross”-build packages with qemu-user. This particular bug was actually discovered while building Debian packages for m68k and sh4 using qemu-user. The problem we have here is we don't know how qemu-user is used in the wild. In my knowledge you are the most involved user, but you're not the only one reporting problem via launchpad. Moreover, distros provide qemu-user statically linked and binfmt configuration files, so we can guess we have other users. And I don't like to break existing things... What I can propose: 1- modify this patch to add a configure option: by default qemu will need the QEMU_ARGV0 but we will be able to define at configure time it always runs with preserve-arg[0] flag enabled (something like "--enable-preserve-arg0") [So debian will be able to provide qemu-user-static with this enabled by default if you're not afraid to break debian users environment] 2- try (again) to push in the kernel the binfmt_misc namespace that allows to have per chroot basis binfmt configuration 3- once 3 done, enable preserve-arg[0] by default Thanks, Laurent