From owner-svn-src-all@FreeBSD.ORG Sun Nov 2 17:19:20 2014 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 2B02FC87; Sun, 2 Nov 2014 17:19:20 +0000 (UTC) Received: from d.mail.sonic.net (d.mail.sonic.net [64.142.111.50]) (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 0EF48BDE; Sun, 2 Nov 2014 17:19:19 +0000 (UTC) Received: from comporellon.tachypleus.net (polaris.tachypleus.net [75.101.50.44]) (authenticated bits=0) by d.mail.sonic.net (8.14.9/8.14.9) with ESMTP id sA2HJH0c010705 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Sun, 2 Nov 2014 09:19:18 -0800 Message-ID: <54566795.6060204@freebsd.org> Date: Sun, 02 Nov 2014 09:19:17 -0800 From: Nathan Whitehorn User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:31.0) Gecko/20100101 Thunderbird/31.1.0 MIME-Version: 1.0 To: Tijl Coosemans Subject: Re: svn commit: r273963 - head/sys/dev/agp References: <201411021126.sA2BQcx4053562@svn.freebsd.org> <54564D5C.8090100@freebsd.org> <20141102170746.287a64e1@kalimero.tijl.coosemans.org> In-Reply-To: <20141102170746.287a64e1@kalimero.tijl.coosemans.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Sonic-CAuth: UmFuZG9tSVZjPVEsLmT18KsWnyG+KUtw/rEBUa/n8BqKiPLo2ZmpNyEf+81NeKQx4DZbC22U6oUl/lCycsa/RmsVpKdIPsvd1D4SdF1eHhc= X-Sonic-ID: C;BqdoYLRi5BGLBCgW/FJGkA== M;9gm2YLRi5BGLBCgW/FJGkA== X-Spam-Flag: No X-Sonic-Spam-Details: 0.0/5.0 by cerberusd Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 02 Nov 2014 17:19:20 -0000 On 11/02/14 08:07, Tijl Coosemans wrote: > On Sun, 02 Nov 2014 07:27:24 -0800 Nathan Whitehorn wrote: >> There is actually a write-combining memory type on PowerPC. You can set >> it the same way as on x86 (with VM_MEMATTR_WRITE_COMBINING). > Yes, that's what the patch does, but in sys/powerpc (aim/mmu_oea.c, > aim/mmu_oea64.c and booke/pmap.c) VM_MEMATTR_WRITE_COMBINING becomes > PTE_I meaning Caching Inhibited. Does powerpc do write-combining for > this type? It is write-combining on all north bridges that support write combining. Regular caching-inhibited is PTE_I | PTE_G. PTE_I means there is no caching, which you want, and PTE_G means that every read/write instruction is a read/write operation of exactly that length exactly right then on the bus. Removing the PTE_G (guarded) flag means the bus is free to do write-combining if it wants to and is the standard way to signal this. > That code also maps VM_MEMATTR_WRITE_BACK to PTE_I by the way. I think > that should be PTE_M (write-back caching + cache coherency). > I think you're right but would like to consider for a few days before changing it. -Nathan