From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Fri, 30 Jul 2010 14:56:25 -0400 From: Vivek Goyal Subject: Re: In place kexec Message-ID: <20100730185625.GD3332@redhat.com> References: <4C51C878.2090102@zytor.com> <20100729191654.GB28704@redhat.com> <20100729125535.85dfd7da.randy.dunlap@oracle.com> <4C524934.5070806@zytor.com> <1280508817.28006.0.camel@macbook.infradead.org> <20100730183446.GC3332@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: David Woodhouse Cc: Randy Dunlap , Neil Horman , "kexec@lists.infradead.org" , Simon Horman , "Eric W. Biederman" , "H. Peter Anvin" , linux-driver@qlogic.com, Andrew Vasquez On Fri, Jul 30, 2010 at 07:50:19PM +0100, David Woodhouse wrote: > On Fri, 30 Jul 2010, Vivek Goyal wrote: > > >On Fri, Jul 30, 2010 at 11:21:42AM -0700, Eric W. Biederman wrote: > >>David Woodhouse writes: > >> > >>>On Thu, 2010-07-29 at 21:41 -0700, Eric W. Biederman wrote: > >>>>There isn't a bus master shut off at the core level. > >>> > >>>Effectively, there is if you have an IOMMU. > >> > >>Depends on the IOMMU. There are several dinky IOMMUs that when you > >>shut them off DMA simply goes around them, and is not stopped. > > > >I think last time we were discussing this for AMD IOMMU where if you > >disable IOMMU, it just kind of become pass through with 1:1 mapping of > >addresses. > > Yeah, don't do that. The IOMMU should be *on*, but without any > active mappings set up. Which is exactly how Linux will set it up at > boot. > So what happens if we tear down the mapping while DMA is on. Vivek _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec