From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manish Jaggi Subject: Re: [PATCH v6 07/30] PCI: Pass PCI domain number combined with root bus number Date: Wed, 18 Mar 2015 09:56:09 +0530 Message-ID: <5508FE61.7070608@caviumnetworks.com> References: <1425868467-9667-1-git-send-email-wangyijing@huawei.com> <1425868467-9667-8-git-send-email-wangyijing@huawei.com> <5507B88D.1020300@caviumnetworks.com> <1426601130.18247.238.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1426601130.18247.238.camel@citrix.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 , xen-devel@lists.xen.org, Yijing Wang List-Id: xen-devel@lists.xenproject.org On Tuesday 17 March 2015 07:35 PM, Ian Campbell wrote: > On Tue, 2015-03-17 at 10:45 +0530, Manish Jaggi wrote: >> On Monday 09 March 2015 08:04 AM, Yijing Wang wrote: >>> Now we could pass PCI domain combined with bus number >>> in u32 argu. Because in arm/arm64, PCI domain number >>> is assigned by pci_bus_assign_domain_nr(). So we leave >>> pci_scan_root_bus() and pci_create_root_bus() in arm/arm64 >>> unchanged. A new function pci_host_assign_domain_nr() >>> will be introduced for arm/arm64 to assign domain number >>> in later patch. >> Hi, >> I think these changes might not be required. We have made very few >> changes in the xen-pcifront to support PCI passthrough in arm64. >> As per xen architecture for a domU only a single pci virtual bus is >> created and all passthrough devices are attached to it. > I guess you are only talking about the changes to xen-pcifront.c? > Otherwise you are ignoring the dom0 case which is exposed to the real > set of PCI root complexes and anyway I'm not sure how "not needed for > Xen domU" translates into not required, since it is clearly required for > other systems. > > Strictly speaking the Xen pciif protocol does support multiple buses, > it's just that the tools, and perhaps kernels, have not yet felt any > need to actually make use of that. > > There doesn't seem to be any harm in updating pcifront to follow this > generic API change. ok. One side question, the function pci_host_assign_domain_nr() which would be introduced in later patch, does it appear to be doing the same binding which we are trying to implement via a pci_host_bridge add hypercall. > > Ian. >