From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH] xen: arm: Enable 1:1 workaround by default Date: Wed, 27 Nov 2013 13:43:37 +0000 Message-ID: <5295F709.5020107@linaro.org> References: <1385554746-21990-1-git-send-email-ian.campbell@citrix.com> <5295F238.8050504@linaro.org> <1385558785.23112.189.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1385558785.23112.189.camel@kazak.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell Cc: stefano.stabellini@eu.citrix.com, tim@xen.org, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 11/27/2013 01:26 PM, Ian Campbell wrote: > On Wed, 2013-11-27 at 13:23 +0000, Julien Grall wrote: >> >> On 11/27/2013 12:19 PM, Ian Campbell wrote: >>> I was just about to send out patches adding the 1:1 workaround to vexpress (the >>> foundation model is a vexpress platfrom with DMA) and sunxi. >>> >>> That would have meant that all platforms now implement the quirk. Instead lets >>> just make it the default and remove the quirk. >>> >>> In the future this will likely be set based on the presence absence of an >>> IOMMU, perhaps with additional overrides by the platform. >>> >>> A command line option no-dom0_11_mapping is provided. >>> >> >> I plan to use the variable in other place, for instance in >> common/memory.c to solve issue between ballooning and 1:1 workaround. >> >> It would be great if we have a function (platform_has_iommu) that we can >> use everywhere. What do you think? > > I think in reality once iommu's arrive it will be a bit more subtle than > their presence or absence, e.g. something (perhaps the platform code) > will need to decide if all the write devices are behind an iommu such > that the 11 can be disabled. > > I can unstatic opt_dom0_11_mapping and stick it in a header though. Or > provide an accessor method. An accessor method sounds better. -- Julien Grall