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X-CSE-ConnectionGUID: 60Oh+49bQPKrnHrqv2nmmQ== X-CSE-MsgGUID: 0up8AYPST+SHbaJuhqcHNA== X-IronPort-AV: E=McAfee;i="6800,10657,11881"; a="86909214" X-IronPort-AV: E=Sophos;i="6.25,233,1779174000"; d="scan'208";a="86909214" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Aug 2026 10:12:30 -0700 X-CSE-ConnectionGUID: sS9GgC9zRHS3uGEmXKz/fA== X-CSE-MsgGUID: ALScGGtvQ6qwJEvTQE0IVA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,233,1779174000"; d="scan'208";a="263458466" Received: from jmaxwel1-mobl.amr.corp.intel.com (HELO [10.125.108.73]) ([10.125.108.73]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Aug 2026 10:12:30 -0700 Message-ID: Date: Thu, 20 Aug 2026 10:12:29 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 2/9] x86/resctrl: Require 64-bit x86 for resctrl support To: "Luck, Tony" , "Chatre, Reinette" , "Chen, Yu C" Cc: "tglx@kernel.org" , "bp@alien8.de" , "mingo@redhat.com" , "dave.hansen@linux.intel.com" , "hpa@zytor.com" , "fenghuay@nvidia.com" , "babu.moger@amd.com" , "chen.yu@linux.dev" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" References: <980c4d9c15862de0b0dbc535b646f6b96ea46abe.1784968626.git.yu.c.chen@intel.com> <6c933b5c-620d-4684-b651-48a7ebdfc956@intel.com> <7911abea-d508-4401-b6de-2f6f598f08bf@intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/20/26 10:01, Luck, Tony wrote: >> To be specific, my comment about RDT not being a "server" feature was made with Apollo >> Lake [1] in mind. That system showed up in scenarios where servers do not typically venture >> and per [1] its max memory size (8GB) is significantly less than what servers can support. > Even with just 8GB you should really use 64-bit. Just in practice, 32-bit is very lightly tested. We're generally not even supporting new CPU features on 32-bit even if the hardware supports it. Think of shadow stacks, for instance. It's actually increasingly hard to even find a modern 32-bit distro. So it really has nothing to do with high memory. It just practically that the arch/x86 32-bit code is increasingly there for legacy reasons. Its testing goes down every day and the testing of *new* features is for all intents and purposes zero. Honestly, the only people who complain about 32-bit support going away are folks who "test" it regularly. It's quite rare to see anyone actually "using" a 32-bit system.