From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D241CC43463 for ; Sun, 20 Sep 2020 18:44:40 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C865B207BB for ; Sun, 20 Sep 2020 18:44:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C865B207BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4Bvc1d2bGtzDqQY for ; Mon, 21 Sep 2020 04:44:37 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=ftp.linux.org.uk (client-ip=2002:c35c:fd02::1; helo=zeniv.linux.org.uk; envelope-from=viro@ftp.linux.org.uk; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Bvbym5VYXzDqHm for ; Mon, 21 Sep 2020 04:42:08 +1000 (AEST) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kK4Hd-002cE4-T4; Sun, 20 Sep 2020 18:41:58 +0000 Date: Sun, 20 Sep 2020 19:41:57 +0100 From: Al Viro To: Matthew Wilcox Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Message-ID: <20200920184157.GP3421308@ZenIV.linux.org.uk> References: <20200918124533.3487701-1-hch@lst.de> <20200918124533.3487701-2-hch@lst.de> <20200920151510.GS32101@casper.infradead.org> <20200920180742.GN3421308@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200920180742.GN3421308@ZenIV.linux.org.uk> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-aio@kvack.org, linux-mips@vger.kernel.org, David Howells , linux-mm@kvack.org, keyrings@vger.kernel.org, sparclinux@vger.kernel.org, Christoph Hellwig , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, x86@kernel.org, Arnd Bergmann , linux-block@vger.kernel.org, io-uring@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jens Axboe , linux-parisc@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Sep 20, 2020 at 07:07:42PM +0100, Al Viro wrote: > /proc/bus/input/devices (fucked bitmap-to-text representation) To illustrate the, er, beauty of that stuff: ; cat32 /proc/bus/input/devices >/tmp/a ; cat /proc/bus/input/devices >/tmp/b ; diff -u /tmp/a /tmp/b|grep '^[-+]' --- /tmp/a 2020-09-20 14:28:43.442560691 -0400 +++ /tmp/b 2020-09-20 14:28:49.018543230 -0400 -B: KEY=1100f 2902000 8380307c f910f001 feffffdf ffefffff ffffffff fffffffe +B: KEY=1100f02902000 8380307cf910f001 feffffdfffefffff fffffffffffffffe -B: KEY=70000 0 0 0 0 0 0 0 0 +B: KEY=70000 0 0 0 0 -B: KEY=420 0 70000 0 0 0 0 0 0 0 0 +B: KEY=420 70000 0 0 0 0 -B: KEY=100000 0 0 0 +B: KEY=10000000000000 0 -B: KEY=4000 0 0 0 0 +B: KEY=4000 0 0 -B: KEY=8000 0 0 0 0 0 1100b 800 2 200000 0 0 0 0 +B: KEY=800000000000 0 0 1100b00000800 200200000 0 0 -B: KEY=3e000b 0 0 0 0 0 0 0 +B: KEY=3e000b00000000 0 0 0 -B: KEY=ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff fffffffe +B: KEY=ffffffffffffffff ffffffffffffffff ffffffffffffffff fffffffffffffffe ; (cat32 being a 32bit binary of cat) All the differences are due to homegrown bitmap-to-text conversion. Note that feeding that into a pipe leaves the recepient with a lovely problem - you can't go by the width of words (they are not zero-padded) and you can't go by the number of words either - it varies from device to device. And there's nothing we can do with that - it's a userland ABI, can't be changed without breaking stuff. I would prefer to avoid additional examples like that, TYVM...