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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id 68-v6sm14027502wmg.26.2018.11.01.02.50.03 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 01 Nov 2018 02:50:04 -0700 (PDT) Date: Thu, 1 Nov 2018 10:50:02 +0100 From: Ingo Molnar To: Zhenzhong Duan Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, konrad.wilk@oracle.com, luto@kernel.org, tglx@linutronix.de, dwmw@amazon.co.uk, bp@suse.de, srinivas.eeda@oracle.com, daniel@iogearbox.net, yamada.masahiro@socionext.com, michal.lkml@markovi.net, peterz@infradead.org, hpa@zytor.com Subject: Re: [PATCH v2 1/2] retpolines: Only enable retpoline support when compiler support it Message-ID: <20181101095002.GA118944@gmail.com> References: <991cbe9b-1e31-4b12-b572-91fde5c79699@default> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <991cbe9b-1e31-4b12-b572-91fde5c79699@default> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Zhenzhong Duan wrote: > Since retpoline capable compilers are widely available, make > CONFIG_RETPOLINE hard depend on it. > > The check of RETPOLINE is changed to CONFIG_RETPOLINE. > > This change is based on suggestion in https://lkml.org/lkml/2018/9/18/1016 > > Signed-off-by: Zhenzhong Duan > Cc: Thomas Gleixner > Cc: Peter Zijlstra Please turn such 'based on suggestions' into proper tags as well, i.e. something like: Suggested-by: David Woodhouse > config RETPOLINE > bool "Avoid speculative indirect branches in kernel" > + depends on $(cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register) || \ > + $(cc-option,-mretpoline-external-thunk) At least a comment should be added that this is the retpoline feature check for GCC and Clang. Also, whitespace damage plus the two options should align vertically. Thanks, Ingo