From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f44.google.com (mail-wr1-f44.google.com [209.85.221.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8960B3F2101 for ; Tue, 17 Mar 2026 16:46:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.44 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773765990; cv=none; b=iegqWHDN+DOWunkIn9x/ULZ6agm4eIssgO2WKKOddNioWPFPBLFtcnnzPsGSZBX+G3NP/TQjL4eJyP1hBBtBLyRfrPjn2iBCQ6bn0ROCrVjOMq0ZbVtTMImDF+Jc1RMLiKSBRIcZYEzq6KnM4CnsQFhL1bTO6JRqAuzKSr7Osww= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773765990; c=relaxed/simple; bh=fVeUggnt90k6wRtkhOWnb6XLB74d5SVvJxMI3b0mvos=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=FvqFe/Tq8YO6tj2HmGuAS5PEdUy9s+utsDFCWAVIjiGbN3Q6fj7fNrSt0obsDPIsE+Joh6IXbKHF9Eg7EshHKcP3JIw81GJKrCXaw0+pgkg3OR+Sos1ooeG43cCRr2JFIW+VHb7AHom9rgAAOYqqsn1eDbnBmugyeuCBbYGPXhg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=OLY2may8; arc=none smtp.client-ip=209.85.221.44 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OLY2may8" Received: by mail-wr1-f44.google.com with SMTP id ffacd0b85a97d-43b3d9d0695so72874f8f.0 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=vger.kernel.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=OLY2may8zfL93T2zSJ3qzrmBgGVOyxl3e0w5b/069jep3Lilqbv6vNhpZcHMSiEMwP 54ygFG8rwMCjbHSWWwtb37p7eWh4yl8P/ja3Kzg/MCrW5aSxvHwphjZLY7HDp8kVo4ED APYKw5WRIXCBFABROI5DVQgLXnO2qCfwBXd9MbeY1a5sjq51LuIDXFMTitpFd8c+t7/a 07V1OrpAW6RYEPLCX+FDbMf/mLVb3NWoo7zy2meo/oDr8kWx4955ZLOx8ZAd2+Sps+72 E+CgB2r34+fCm8zA2W+Cv+Me5uXXSQxC7ArWcvylBbKESwmcXrR8/z5NbL5T4fhj3i2j hddQ== 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=lxQzHG4sMZVJzHfO9nhPguMiCescSnNbE0xs3bmuSJHg6AweSmTV/Mi8EegzNBrI66 E9/8jzIBfXbDwjlgrlR8cgjupPfN2xyLVMm8uK/WveHll2TICPtaF0cB33IvoK83TYef dXlp4lTXgixbk7PO2+q3qtkIiEdd+YuZxkQAq5tVGglT7J1iYHZCrzJu3jeJB9dFYzoh LhRSaiBtM8ts4dOCkbKAMzpHV7gay7vGWx0TiB2c9FFEABiwJIrb8VQt7x0z1tW/3PAH jt1iboJ6n+kVNEuo4ntUlCpYowQnTUqzP7FNxTNftv51nr73rrXVsBXv1AEy96fJeWq3 t5IA== X-Forwarded-Encrypted: i=1; AJvYcCVXkOA+h4/lFwCiHKVxzlQ5VPpXlYDOCvcSlifqbCC9WsPjWmqeP7li3mmXfT2J/phkUBjvLAqRj0caDdc=@vger.kernel.org X-Gm-Message-State: AOJu0YzEmdlNTDr5eSW4SPN+Fzt8cjN2T/WLrHmkNqR2JyrFzPbQpCbN MAXJvL0hnc773x/WThY2DAjU7wUZ+zHLBOnO/d0BDda0CsXveGv/XL8X X-Gm-Gg: ATEYQzzM3HqTFfPWt/iR60WpGQ/01Otdf0VBUWyOBU937Yn5Wr/0FjSqaG6gRTmAVvP JR8kEOhUr2PqX8a20w8sYkISJ3+Av2bHORwVidfD7mcWU4xndjDOPzhpDezG2rEIMwKjx28rIdo FV34cFatmGgc2Y4OldkubV051jy/5oXUfhXb+6Q2+byP9qfsxVs1bfM9+1sRnjLvkbt/GT5t8qC Uh1AXr4U2FMp7W3LbFL28C0+vsXF45t+OlzI9tNZSutoWccEBSDVWdtgVQmBFT/CnTklmA8KPFJ ydxCVcTaG1rCk2E5Yvczzyb424rVdo9Cm+yGyF/a2Icspn6V8Gwhv9o6APDxUgdeTf9I3MmHsv6 Ag8W7bxG6W5JxZqLAOGwbCCxwczrw7HO8dRuCsa+a8JiptTliByJ2Rgub8Fz0LyWkQlBpHhUurV 8y2JqMixJ4Twat65AeUJnTL6IqL6u9nwA+t1l6EkU2BCX1IeUymKvrQF4UnzjGw74F 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 > > > >