From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx49I8UnwTVr9ztxPtVky7nsYwerbmyx4+owJiE/uuI8cd3n08/n7PyBVv5qsg5lXBmxch1Wo ARC-Seal: i=1; a=rsa-sha256; t=1522833554; cv=none; d=google.com; s=arc-20160816; b=g7ARXaOGX0lIIuR3i3jn6O2NlIoUln8HWQfm1Ef841mtBzOAr6Hn6iji+8u4g6UJSO ylzSYCJ8Faz7k+UWTcO2cJis/6AqJ7uZDAnLL33wv2kwIvgnPXMOa0H3W/p4KQ7FYew3 JBorNZrVqHKE2n1U4CF9H8RHAA8KHlz4bV46wwQO+CC1GgaGB1LunCjJsUSP8uxLjeGQ PqwKHPXUZ0I/EVfPsY1LkviZxive3V0ujlruRJCUQL7oSkyrQZw1oMxoKLHyx1bk3g+b 1VJwXxz6H8zF+HgmflAWG334J//ed5HGbKyxwhc1wnYXVzT/eDRkyo0FT4weWuNYCmQi WqEw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=6rrBUm09oTQalFRxSqKf6vxMKoxP128izyMvI8yvkl4=; b=AUBHqBWe878RsrV9ImgOCHR5wkkCPWkTzMnKe5o/I+NcAnyukFKttLap5POTMCAt+R ujBsc4RXal/6XTnuIm8BcGjbAEMrz0ooh5nFg1na6fGqwV6UpbCmSfJs5BBq/tpEtHRl rVNGZgS7n4dT75TpFkS0jde3RSjZU4vfOqpuDyGjZy0GvMBSjkMexUrR8lesDWTg5rcu vTU0O7Rru1kcPdoPwZ9W1tuGeWtTQLaDq8KXkOGwEje+R1GGihuthb/kF/q+eggXwbcr 1fzhXtwk1EGSPBvC4yr7BKFrNNSLSXKoOap9n3goKDUiK/QpLCcU26ao3WSQWRZODFfi ShKg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=kh3koJNt; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 198.137.202.133 as permitted sender) smtp.mailfrom=peterz@infradead.org Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=kh3koJNt; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 198.137.202.133 as permitted sender) smtp.mailfrom=peterz@infradead.org Date: Wed, 4 Apr 2018 11:19:09 +0200 From: Peter Zijlstra To: Nick Desaulniers Cc: Matthias Kaehlcke , Ingo Molnar , Linus Torvalds , LKML , Thomas Gleixner , Andrew Morton , James Y Knight , Chandler Carruth , Stephen Hines , Kees Cook , groeck@chromium.org, Greg Hackmann , Greg KH Subject: Re: [GIT PULL] x86/build changes for v4.17 Message-ID: <20180404091909.GH4082@hirez.programming.kicks-ass.net> References: <20180402095033.nfzcrmxvpm46dhbl@gmail.com> <20180403085904.GY4082@hirez.programming.kicks-ass.net> <20180403095118.rpf7tj577dppvx7d@gmail.com> <20180403180658.GE87376@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.3 (2018-01-21) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcSW1wb3J0YW50Ig==?= X-GMAIL-THRID: =?utf-8?q?1596675801568391777?= X-GMAIL-MSGID: =?utf-8?q?1596806717508595645?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, Apr 03, 2018 at 09:58:03PM +0000, Nick Desaulniers wrote: > Speaking more with our internal LLVM teams, there ARE a few different > approaches to implementing asm-goto in LLVM proposed, by external parties > to Google. These proposals haven't progressed to code review, so we've > asked our LLVM teams to reignite these discussions with increased priority, > if not implement the feature outright. We (Google kernel AND llvm hackers) > are committed to supporting the Linux kernel being built with Clang. > > I can see both sides where eventually a long-requested feature-request > should come to a head, especially with good evidence ( > https://lkml.org/lkml/2018/2/14/895), but just as you wouldn't accept a > patch that doesn't compile with GCC, I'd like to request that we don't > merge patches that fail to compile with Clang (or at least start to think > what that might look like). Again, I ask what the plans are for asm-cc-output, hard depending on that is a few years out I imagine, but if you don't promise feature parity for all the features we use, I can see this all happening again. Also, it would be good to get input on the whole memory model situation; esp. with people looking to do LTO builds, the C/C++ memory model can cause us quite some grief, for specifics I feel we should start a new thread. But this is another issue that's been raised several times without feedback.