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X-CSE-ConnectionGUID: A1ZewRheTOO7C5tR0v5alw== X-CSE-MsgGUID: LqC9SG9YSsuYyWVGoNOesA== X-IronPort-AV: E=McAfee;i="6800,10657,11520"; a="57579074" X-IronPort-AV: E=Sophos;i="6.17,287,1747724400"; d="scan'208";a="57579074" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2025 14:07:02 -0700 X-CSE-ConnectionGUID: kPrcgclvR6mNvHYoXnY6uQ== X-CSE-MsgGUID: I4M+uEG1RNSG7G5iQibY1g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,287,1747724400"; d="scan'208";a="203752285" Received: from cmdeoliv-mobl4.amr.corp.intel.com (HELO [10.125.111.131]) ([10.125.111.131]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2025 14:07:01 -0700 Message-ID: Date: Wed, 13 Aug 2025 14:07:00 -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 v3 1/1] x86/fred: Remove ENDBR64 from FRED entry points To: "Xin Li (Intel)" , linux-kernel@vger.kernel.org Cc: luto@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, jmill@asu.edu, peterz@infradead.org, andrew.cooper3@citrix.com, stable@vger.kernel.org References: <20250716063320.1337818-1-xin@zytor.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 7/15/25 23:33, Xin Li (Intel) wrote: > The FRED specification has been changed in v9.0 to state that there > is no need for FRED event handlers to begin with ENDBR64, because > in the presence of supervisor indirect branch tracking, FRED event > delivery does not enter the WAIT_FOR_ENDBRANCH state. > > As a result, remove ENDBR64 from FRED entry points. So, the spec is being updated or has been updated to reflect the new architecture, right? Remind me, are there no FRED systems out in the wild today, so we don't have to worry about breaking anything?