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[209.85.167.53]) by smtp.gmail.com with ESMTPSA id f20-v6sm1647227ljk.33.2019.02.15.16.22.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Feb 2019 16:22:04 -0800 (PST) Received: by mail-lf1-f53.google.com with SMTP id h10so8222966lfc.12 for ; Fri, 15 Feb 2019 16:22:03 -0800 (PST) X-Received: by 2002:a19:ab09:: with SMTP id u9mr6928685lfe.149.1550276523131; Fri, 15 Feb 2019 16:22:03 -0800 (PST) MIME-Version: 1.0 References: <20190213144145.GY32494@hirez.programming.kicks-ass.net> <20190213154532.GQ32534@hirez.programming.kicks-ass.net> <20190213222146.GC32494@hirez.programming.kicks-ass.net> <20190214101429.GD32494@hirez.programming.kicks-ass.net> <20190214193432.GR32477@hirez.programming.kicks-ass.net> <20190215174034.GP32494@hirez.programming.kicks-ass.net> <20190215233414.GS32534@hirez.programming.kicks-ass.net> In-Reply-To: <20190215233414.GS32534@hirez.programming.kicks-ass.net> From: Linus Torvalds Date: Fri, 15 Feb 2019 16:21:46 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] sched/x86: Save [ER]FLAGS on context switch To: Peter Zijlstra X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190215_162207_823953_CE4E63B0 X-CRM114-Status: GOOD ( 12.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Denys Vlasenko , Josh Poimboeuf , Julien Thierry , Brian Gerst , "H. Peter Anvin" , Will Deacon , Linux Kernel Mailing List , Andy Lutomirski , valentin.schneider@arm.com, Ingo Molnar , James Morse , Andy Lutomirski , Catalin Marinas , Borislav Petkov , Thomas Gleixner , Ingo Molnar , "linux-alpha@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Feb 15, 2019 at 3:34 PM Peter Zijlstra wrote: > > Now, EFLAGS bit 1 is supposedly always 1, but it really doesn't seem to > matter for POPF. Correct, it's "read as 1", you can try to write it and it doesn't matter. > I went through the other flags, and aside from VIP/VIF (I've no clue), > they looks like 0 should be just fine. So 0 is a perfectly valid initializer in the sense that it _works_, I just want it to be something that was thought about, not just a random "initialize to zero" without thinking. Even just a comment about it would be fine. But it might also be good to show that it's an explicit eflags value and just use X86_EFLAGS_FIXED as the initializer. Linus _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel