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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E0FB0F483C0 for ; Mon, 23 Mar 2026 16:04:09 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A2ABB10E46F; Mon, 23 Mar 2026 16:04:09 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="Pw61+tJp"; dkim-atps=neutral Received: from mail-wm1-f43.google.com (mail-wm1-f43.google.com [209.85.128.43]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0F24A10E4AA for ; Tue, 17 Mar 2026 14:56:51 +0000 (UTC) Received: by mail-wm1-f43.google.com with SMTP id 5b1f17b1804b1-48628ce9ab5so10591515e9.2 for ; Tue, 17 Mar 2026 07:56:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1773759409; x=1774364209; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=fV0vsElu+7ZDP0k7EZQosqrMEMjbFMIbCAe1EPTu8LI=; b=Pw61+tJpY9hG/aPfRgW282RX3RujtlF9GAUx8/P9W/sa6dqj57+1TG3YUP91JfAmSV 9ZryN2EKZi/08kq46waJzBal2xAYkeefAViJX13qERt+7PNqLk1Hd/MM0LJjEO7ebSEP uZjGDQEbu/4reL11ekjxWnrzXYJggeSXZ104ShZKlvB1TYuSLuDGa/jxThcvEWQTY9md 83or+Iuee0wqWgvlYPvvpTAFJR1Slv8Pzu/v878MIaN2p2AFygs+4KR0viDNjDW4NXyn uK5KjRkbwaYi0+qEtIc6av+FKUCUJ5wIxGdON3qrsdaz5KvStMbRH2RQah3KO5peWiNi Ug9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773759409; x=1774364209; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=fV0vsElu+7ZDP0k7EZQosqrMEMjbFMIbCAe1EPTu8LI=; b=Nno5nY4tn3+lOswNUMo1yCSGObQHyz6Is7mFwZcZ6ZzowSrvwz3uIYH69ZlkbggnF6 c2727sYJzkq8Tc8qtJTWEAF5dF07VQ6dy94UVMDym8BHVdch96QBtxcJ9DBIvnc6tfFx 61lNr2xSiAxcPDE+MZWawGQ2qJqLb4fw7iv1G6hbb813gSSCqET7v/rjymmpz29LvoJz l5p6g3Eq/147JlhTr/n0GBomqgKilbM9PTujutFNDAev+KXxxblezESmAge4vHuZHs0U F10/4jqnmklc0YX0m481NinonqlQxvbKphuRKjnsyX2L/4FBqcQkcjiwJrMOYyOCtHbM YEyQ== X-Forwarded-Encrypted: i=1; AJvYcCVcWooOVD4MWS7jRh+1uRvGP/zUjyZWPJyjOXs8zFetQbPxvRH/3Pc0aRentXcqu685NZf6o9/giw==@lists.freedesktop.org X-Gm-Message-State: AOJu0YwjRDxtWa1UMUjthzXAyIY+4195qL7fkZsyLdpdKdpJ0mxlpd1I eaywFbfXmgQtFGFVKZ4yTm0xJTxcJLwjzT0JkmPOGkN5O6j5yqyASEpq X-Gm-Gg: ATEYQzwfvYUVQC+QyZqwXLw6LRbIBmQE6z4QZ6FCmNVsY3z2qvavhMkGxCJTztd3XCI kUjNPBsUCVIc51Qzg6Rxt0bFL1P2gnvJFjOQtuO0LM9l/fCJuqJNdKNs7mcNxV8M6/h24+Uj0eF U+SPX8P7eZrwnnJwDiUGhAMAQg/L24mNlAyJWE7ENoAKF3ah/LwZmyTSjLGuy4jf1r0XDd74Jxg mowfqmrh1FWtwuYKCOrbTuGXZw7NKt1TCHDGZff7ZbPQqIUXsGXQP85nttHiDU2G8dO/9PZ1UMk OjT0jTqfNkDDWE23pzZRZLrRthBQcZ9rwv442LQdqCgYE56cdGtaCIEwanZpdBYlZtTozs9OEBw qBqtuTgp73JSb4JrnpBivnFvPP4bRfiX8e/8ogA+K15wFwmRgSz7J8QX0eg2jYETvMBJs4VcoH8 7WvA5grTdLKg/T3yYt+TbLiTaV+P0IfEN/D4qS8u33Dsh2O8HS3OiQfNJzQz5SI1yt X-Received: by 2002:a05:600c:1d1a:b0:485:3d00:efd with SMTP id 5b1f17b1804b1-485566cfacbmr307335885e9.7.1773759408795; Tue, 17 Mar 2026 07:56:48 -0700 (PDT) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4856ea97e8esm74472665e9.5.2026.03.17.07.56.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 07:56:48 -0700 (PDT) Date: Tue, 17 Mar 2026 14:56:47 +0000 From: David Laight To: "Arnd Bergmann" Cc: "Matt Roper" , "Arnd Bergmann" , "Matthew Brost" , Thomas =?UTF-8?B?SGVsbHN0csO2bQ==?= , "Rodrigo Vivi" , "Dave Airlie" , "Simona Vetter" , "Dnyaneshwar Bhadane" , "Lucas De Marchi" , "Tvrtko Ursulin" , "Umesh Nerlige Ramappa" , "Raag Jadav" , "Niranjana Vishwanathapura" , intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/xe: use %z format string for ptrdiff_t Message-ID: <20260317145647.0d5de2a1@pumpkin> In-Reply-To: References: <20260316224357.658520-1-arnd@kernel.org> <20260316225118.GD2729713@mdroper-desk1.amr.corp.intel.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Mon, 23 Mar 2026 16:04:08 +0000 X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Tue, 17 Mar 2026 00:07:57 +0100 "Arnd Bergmann" wrote: > On Mon, Mar 16, 2026, at 23:51, Matt Roper wrote: > > On Mon, Mar 16, 2026 at 11:43:46PM +0100, Arnd Bergmann wrote: > >> From: Arnd Bergmann > >> > >> ptrdiff_t, size_t and long are the same size on all supported architectures, > >> but gcc requires the use of the %zx modifier instead of %lx. On 32-bit > > > > Nathan Chancellor just sent a fix here: > > > > https://lore.kernel.org/all/20260316-drm-xe-fix-32-bit-wformat-ptrdiff-v1-1-0108b10b2b6b@kernel.org/ > > > > His solution uses %tx rather than %zx, which according to > > Documentation/core-api/printk-formats.rst sounds like it's probably the > > most accurate format string for this case? > > > > Right, Nathan's version is correct. I wasn't aware that size_t > and ptrdiff_t have different modifiers. Consider: void foo(size_t len) { char *p = malloc(len); char *end = p + len; ptrdiff_t diff = p - end; printf("len %zu, diff %td\n", len, diff); free(p); } Clearly foo(5) output "5 -5". But what about foo(5u << 29) on a 32bit system with a large unlimit and a big enough hole in the address space. More likely would be something running on an x86 in real mode. There malloc(65000) might be reasonable, so size_t would be unsigned int but ptrdiff_t would need to be a signed 32bit type. Of course, in linux, they are all 'long'. David > > Arnd >