From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: Assigning contiguous memory to a driver domain Date: Mon, 20 Sep 2010 13:27:24 -0700 Message-ID: <4C97C3AC.90207@goop.org> References: <4C90B31902000078000163E8@vpn.id2.novell.com> <4C90A32A.7010803@invisiblethingslab.com> <4C90C3200200007800016442@vpn.id2.novell.com> <4C90A8E4.9090004@invisiblethingslab.com> <4C90CF39020000780001647E@vpn.id2.novell.com> <87pqwfgqvt.fsf@frosties.localdomain> <20100915120626.GA2024@email> <4C90EB1102000078000164C6@vpn.id2.novell.com> <20100915144413.GB2098@email> <4C91027802000078000165E8@vpn.id2.novell.com> <20100920194836.GA25803@dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100920194836.GA25803@dumpdata.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Konrad Rzeszutek Wilk Cc: Dan Magenheimer , xen-devel@lists.xensource.com, Joanna Rutkowska , Jan Beulich , Rafal Wojtczuk List-Id: xen-devel@lists.xenproject.org On 09/20/2010 12:48 PM, Konrad Rzeszutek Wilk wrote: > Let me expand this. During bootup Xen-SWIOTLB (which for DomU you have > to enable via the 'iommu=soft'), allocated 32 2MB chunks of contingous > memory under the 4GB limit. Those chunks stay in DomU and are used > during the the runtime of the DomU. They don't go back to Xen unless the > domain has been terminated. Any of the DMA operations that any driver > does go through the SWIOTLB bufer if the physical (mfn) for the DMA is > outside the driver capabilities (say, your ping buffer is allocated above > the 4GB, and your r8169 can only do 32-bit, then SWIOTLB would be utilized > to "bounce" the memory). BTW, are there any hooks to make sure these pages are still contiguous after migration/restore? J