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X-CSE-ConnectionGUID: RmwCja+MSfacNQrkcS4O1A== X-CSE-MsgGUID: nv9Tf8eAQo2hYAiUT3aekg== X-IronPort-AV: E=McAfee;i="6700,10204,11453"; a="61638909" X-IronPort-AV: E=Sophos;i="6.16,206,1744095600"; d="scan'208";a="61638909" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jun 2025 09:29:49 -0700 X-CSE-ConnectionGUID: P0YjZXHmQ36BAg45YXlVhw== X-CSE-MsgGUID: Ed1VRmsWRESM5FaNybHZfg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,206,1744095600"; d="scan'208";a="150063482" Received: from tjmaciei-mobl5.ger.corp.intel.com (HELO [10.125.110.192]) ([10.125.110.192]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jun 2025 09:29:48 -0700 Message-ID: <373bbdbb-1755-425c-90bf-1bb7d40944cb@intel.com> Date: Tue, 3 Jun 2025 09:29:48 -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] x86/kerrnel/FPU: clear MP bit of cr0 To: Khalid Ali , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com Cc: x86@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org References: <20250526082414.689-1-khaliidcaliy@gmail.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 5/26/25 01:22, Khalid Ali wrote: > Clear MP bit when initializing x87 FPU, since what it does > is making WAIT/FWAIT instructions to react to setting of TS flag. > Right now TS bit is cleared so MP should be cleared, as it is not > needed. This should set the bit in defined state. Hi Khalid, What is the user visible result of this change? Could you also give us a little more background about how you came upon this problem? Was a program misbehaving and you narrowed it down to this? Did you find it by inspection?