From owner-svn-src-all@freebsd.org  Fri Oct 23 15:46:32 2015
Return-Path: <owner-svn-src-all@freebsd.org>
Delivered-To: svn-src-all@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 B3B9FA1D9AA;
 Fri, 23 Oct 2015 15:46:32 +0000 (UTC)
 (envelope-from prvs=731ed1d6e=roger.pau@citrix.com)
Received: from SMTP02.CITRIX.COM (smtp02.citrix.com [66.165.176.63])
 (using TLSv1 with cipher RC4-SHA (128/128 bits))
 (Client CN "mail.citrix.com",
 Issuer "Verizon Public SureServer CA G14-SHA2" (verified OK))
 by mx1.freebsd.org (Postfix) with ESMTPS id EF9E0AB9;
 Fri, 23 Oct 2015 15:46:31 +0000 (UTC)
 (envelope-from prvs=731ed1d6e=roger.pau@citrix.com)
X-IronPort-AV: E=Sophos;i="5.20,187,1444694400"; d="scan'208";a="312620684"
Subject: Re: svn commit: r289834 - head/sys/x86/x86
To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= <royger@FreeBSD.org>,
 <src-committers@freebsd.org>, <svn-src-all@freebsd.org>,
 <svn-src-head@freebsd.org>
References: <201510231539.t9NFdxPe018130@repo.freebsd.org>
From: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= <roger.pau@citrix.com>
Message-ID: <562A564D.9080703@citrix.com>
Date: Fri, 23 Oct 2015 17:46:21 +0200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:38.0)
 Gecko/20100101 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <201510231539.t9NFdxPe018130@repo.freebsd.org>
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
X-DLP: MIA1
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.20
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
 user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all/>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 23 Oct 2015 15:46:32 -0000

El 23/10/15 a les 17.39, Roger Pau Monné ha escrit:
> Author: royger
> Date: Fri Oct 23 15:39:59 2015
> New Revision: 289834
> URL: https://svnweb.freebsd.org/changeset/base/289834
> 
> Log:
>   x86/dma_bounce: rework _bus_dmamap_load_ma implementation
>   
>   The implementation of bus_dmamap_load_ma_triv currently calls
>   _bus_dmamap_load_phys on each page that is part of the passed in buffer.
>   Since each page is treated as an individual buffer, the resulting behaviour
>   is different from the behaviour of _bus_dmamap_load_buffer. This breaks
>   certain drivers, like Xen blkfront.
>   
>   If an unmapped buffer of size 4096 that starts at offset 13 into the first
>   page is passed to the current _bus_dmamap_load_ma implementation (so the ma
>   array contains two pages), the result is that two segments are created, one
>   with a size of 4083 and the other with size 13 (because two independant
>   calls to _bus_dmamap_load_phys are performed, one for each physical page).
>   If the same is done with a mapped buffer and calling _bus_dmamap_load_buffer
>   the result is that only one segment is created, with a size of 4096.
>   
>   This patch relegates the usage of bus_dmamap_load_ma_triv in x86 bounce
>   buffer code to drivers requesting BUS_DMA_KEEP_PG_OFFSET and implements
>   _bus_dmamap_load_ma so that it's behaviour is the same as the mapped version
>   (_bus_dmamap_load_buffer). This patch only modifies the x86 bounce buffer
>   code, other arches are left untouched.
>   
>   Reviewed by:		kib, jah
>   Differential Revision:	https://reviews.freebsd.org/D888
>   Sponsored by:		Citrix Systems R&D

Forgot to add:

MFC after:	2 weeks

Roger.