> -----Original Message----- > From: Jan Beulich [mailto:jbeul...@suse.com] > Sent: 04 September 2018 09:47 > To: Kevin Tian <kevin.t...@intel.com> > Cc: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>; Julien Grall > <julien.gr...@arm.com>; Paul Durrant <paul.durr...@citrix.com>; Stefano > Stabellini <sstabell...@kernel.org>; xen-devel <xen- > de...@lists.xenproject.org> > Subject: Re: [Xen-devel] [PATCH v6 01/14] iommu: introduce the concept of > BFN... > > >>> On 04.09.18 at 10:37, <kevin.t...@intel.com> wrote: > >> From: Jan Beulich [mailto:jbeul...@suse.com] > >> Sent: Tuesday, September 4, 2018 4:33 PM > >> > > >> > bus address is commonly used along with physical/virtual address, to > >> > represent different views between devices and CPU. From that angle > >> > I think BFN is a clear term in this context. btw it is not necessary to > >> > differentiate GBFN and MBFN since there is only one BFN view per > >> > device. > >> > >> Sure, but you neglect the presence of one or more IOMMUs when > >> you say "between devices and CPU". There addresses prior to and > >> after IOMMU translation are distinct, and while the one before the > >> translation matches the device view, the one after translation does > >> not necessarily match the CPU view. Hence there are two "bus" > >> frame numbers here - one representing the device view, and the > >> other representing the IOMMU (output) view. > >> > > > > I didn't get. the output address from IOMMU is the one sent to > > memory controller, same as the one sent from CPU. > > That's on present x86 systems, but aiui not in the general case. The > terminology to be used in Xen should fit the general case though.
So your concern is cascaded IOMMUs? Paul > > Jan > _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
