From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) by kanga.kvack.org (Postfix) with ESMTP id 586FF6B028F for ; Thu, 1 Oct 2015 07:51:47 -0400 (EDT) Received: by wiclk2 with SMTP id lk2so29310433wic.0 for ; Thu, 01 Oct 2015 04:51:46 -0700 (PDT) Received: from Galois.linutronix.de (Galois.linutronix.de. [2001:470:1f0b:db:abcd:42:0:1]) by mx.google.com with ESMTPS id q1si3277838wif.64.2015.10.01.04.51.46 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Thu, 01 Oct 2015 04:51:46 -0700 (PDT) Date: Thu, 1 Oct 2015 13:51:05 +0200 (CEST) From: Thomas Gleixner Subject: Re: [PATCH 06/25] x86, pkeys: PTE bits for storing protection key In-Reply-To: <20150928191819.F8EB3C51@viggo.jf.intel.com> Message-ID: References: <20150928191817.035A64E2@viggo.jf.intel.com> <20150928191819.F8EB3C51@viggo.jf.intel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: borntraeger@de.ibm.com, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, dave.hansen@linux.intel.com On Mon, 28 Sep 2015, Dave Hansen wrote: > From: Dave Hansen > > Previous documentation has referred to these 4 bits as "ignored". > That means that software could have made use of them. But, as > far as I know, the kernel never used them. > > They are still ignored when protection keys is not enabled, so > they could theoretically still get used for software purposes. > > We also implement "empty" versions so that code that references > to them can be optimized away by the compiler when the config > option is not enabled. > > Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org