From owner-svn-src-head@freebsd.org Sun Dec 4 22:55:23 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C89D8C67896 for ; Sun, 4 Dec 2016 22:55:23 +0000 (UTC) (envelope-from ian@freebsd.org) Received: from outbound1b.ore.mailhop.org (outbound1b.ore.mailhop.org [54.200.247.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id ADF15841 for ; Sun, 4 Dec 2016 22:55:23 +0000 (UTC) (envelope-from ian@freebsd.org) X-MHO-User: bcdb6b86-ba74-11e6-9f67-d3961ed5a660 X-Report-Abuse-To: https://support.duocircle.com/support/solutions/articles/5000540958-duocircle-standard-smtp-abuse-information X-Originating-IP: 73.78.92.27 X-Mail-Handler: DuoCircle Outbound SMTP Received: from ilsoft.org (unknown [73.78.92.27]) by outbound1.ore.mailhop.org (Halon) with ESMTPSA id bcdb6b86-ba74-11e6-9f67-d3961ed5a660; Sun, 04 Dec 2016 22:55:23 +0000 (UTC) Received: from rev (rev [172.22.42.240]) by ilsoft.org (8.15.2/8.15.2) with ESMTP id uB4MtErJ012125; Sun, 4 Dec 2016 15:55:14 -0700 (MST) (envelope-from ian@freebsd.org) Message-ID: <1480892114.1889.243.camel@freebsd.org> Subject: Re: svn commit: r309531 - head/sys/arm/include From: Ian Lepore To: John Baldwin , Michal Meloun Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Date: Sun, 04 Dec 2016 15:55:14 -0700 In-Reply-To: <1605461.LLfnXX4YB2@ralph.baldwin.cx> References: <201612041527.uB4FRduc064051@repo.freebsd.org> <1605461.LLfnXX4YB2@ralph.baldwin.cx> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.18.5.1 FreeBSD GNOME Team Port Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Dec 2016 22:55:23 -0000 On Sun, 2016-12-04 at 13:43 -0800, John Baldwin wrote: > On Sunday, December 04, 2016 03:27:39 PM Michal Meloun wrote: > > > > Author: mmel > > Date: Sun Dec  4 15:27:39 2016 > > New Revision: 309531 > > URL: https://svnweb.freebsd.org/changeset/base/309531 > > > > Log: > >   Implement fake pmap_mapdev_attr() for ARMv6. > >   This function is referenced, but never called from DRM2 code. > > Also, > >   real behavior of pmap_mapdev_attr() in ARM world is unclear as we > > don't > >   have any additional attribute for a device memory type. > You have VM_MEMATTR constants on ARM though.  Some devices might want > a > WB mapping (e.g. for a prefetchable memory BAR) rather than UC. > On ARM, 'DEVICE' memory is its own type/attribute and it can't usefully be changed (if you were to change it, it would no longer be device memory, it would be some other type).  If this function is being used to map main memory just because that memory happens to be used in some device driver, then that's a usage model that just doesn't map usefully to arm memory semantics. -- Ian