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 D145EFED9ED for ; Tue, 17 Mar 2026 16:46:29 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3F70D10E576; Tue, 17 Mar 2026 16:46:29 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="SwRI3JSX"; dkim-atps=neutral Received: from mail-wr1-f45.google.com (mail-wr1-f45.google.com [209.85.221.45]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4F5AC10E6EB for ; Tue, 17 Mar 2026 16:46:28 +0000 (UTC) Received: by mail-wr1-f45.google.com with SMTP id ffacd0b85a97d-439b6d9c981so48869f8f.1 for ; Tue, 17 Mar 2026 09:46:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1773765987; x=1774370787; 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=++LJXc5vhHGA5o4goL+ihczkLTg8146WStrt9s5OCas=; b=SwRI3JSXZUxoEGFOU43jTcPqwQ9aJjRvI5ay/dXxPLM4j6wnbT8giEIUKimSXHOMUr V1DouIqzSWYTisMbaGnzt7KsRBIwUZYepeeGdZD3BB0AwhKOEh1nHXKT4alQRfzolmcT fUUQvu05b5sHo/flsvCH5902rxLD3y5l6knPPs3yw4EvqWThtD4fjS//B6QIYd0P/EG6 gN8XfeMjVBRN4X5x5YVFbSxczMkKoGy4JcFK+J9v1srZJRw7F+Zi2CQZN2QyShJtZZOc bFIntEVtkQGu5H+QTrBVJi1+uxWGTb2WA+DAFj+7SXZ4NV4pQX55dDikx/S2g6UGWF1L XKlw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773765987; x=1774370787; 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=++LJXc5vhHGA5o4goL+ihczkLTg8146WStrt9s5OCas=; b=Z/zSUz56qoK3ToK1tYP7trsxYjX+KVtTBO9zpptkAJmnTn26F5KK/oh2QTLZI4d0gQ GgWnJBSkcSVbThrCT3ZZFOikta+gZFTKRYVu8L7p0xnhSlOktUtjZZyq1dympAcX1WWX OD6ZTnY+95b0f2MWJ7cSxqL1zHz+n5rr0CF5+Q/s1ADF3nlnYNUEtFfHr5zuTo2IONag ULLWe6yfSJeMvvc0BeCAXtQIxUyJAulU/vwvIXK489IfASWUtJ77RgXvdyQ66SV94EcM l4blFagZNrxWD9o00L0v3ky2ApeMScUYKH8Q37rtHaGw94ICXB3O208IB+wFNic6/5Bg xdtA== X-Forwarded-Encrypted: i=1; AJvYcCU5RgfJKn8wKIcTK3FJXpQlLuoieswu9TbzhKmEDBvKWdhEkj6aMGu+UPoo5IVh3Ob51tVdH+mlbQc=@lists.freedesktop.org X-Gm-Message-State: AOJu0YwKAjRkFgI6FTo76qC4trK+uZairf1ZDSH9RIOncSm6v6RT6m9D 2pzXheVUd6Sc4PG5WRaJ361WGNZ1DuRrviB4zUkl3/6hDFbHTqiP//rx X-Gm-Gg: ATEYQzxR/SPigQXdb/tBAPJQvMSHpvxA4jqoNBEirXdHY9Bf5QHzk50wIpH0a+T8nkw /v7w3dz4MGJG+yNEQ3tAYGPSX4mvQPbvvvyB6xxJW+Lq7j3IrgevcG3AhSpUux7G92rWhzNVHNQ 5HqLo4/cSScAUv69ijFX6FH777/TAHFo5/IKIG1x06fJ/h0RyttCNn5/RL6ENSKZbKqgW6UQnm4 jt1MGGKXZ5vraPpL993GPLaKegF6TIqoQ1HxHKWL5ynOAv4yrozZ4JRaTvPR53pLLRfXkkSuU3f 72UQyyvTQaTLZX4IU+qUgSFm+NOF7y834HjmhVGFt+Ab2DhjzwtDHLDlvITlmTKXQD9o30wz5kv BErjhgJvh5AuG9+qlJzVN0X3dF5NDJ4EhkE3Ty+e+f/hzzeWQ/JM85PebUJL2CTWdACU649X2i6 l94SOsyTYczTcunLE8L5wJRy+QWoWxHkyXDxOg0tdpio95g70lUU1BoaG54IK9P19l X-Received: by 2002:a5d:5f82:0:b0:439:df59:abc5 with SMTP id ffacd0b85a97d-43b4981a167mr7391373f8f.12.1773765986492; Tue, 17 Mar 2026 09:46:26 -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 ffacd0b85a97d-43b518a3e3csm566981f8f.35.2026.03.17.09.46.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 09:46:26 -0700 (PDT) Date: Tue, 17 Mar 2026 16:46:24 +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: <20260317164624.79843d2a@pumpkin> In-Reply-To: <20260317145647.0d5de2a1@pumpkin> References: <20260316224357.658520-1-arnd@kernel.org> <20260316225118.GD2729713@mdroper-desk1.amr.corp.intel.com> <20260317145647.0d5de2a1@pumpkin> 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-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, 17 Mar 2026 14:56:47 +0000 David Laight wrote: > 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'. I should have said 'the same size as long'. > > David > > > > > > Arnd > > > >