From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yijing Wang Subject: Re: [PATCH v6 07/30] PCI: Pass PCI domain number combined with root bus number Date: Wed, 18 Mar 2015 13:56:07 +0800 Message-ID: <55091377.3060607@huawei.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> <5508FE61.7070608@caviumnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5508FE61.7070608@caviumnetworks.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: Manish Jaggi , Ian Campbell , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 2015/3/18 12:26, Manish Jaggi wrote: > > 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. pci_host_assign_domain_nr() will be called only when CONFIG_PCI_DOMAINS_GENERIC enabled, now mostly be used in arm/arm64. Thanks! Yijing. > >> >> Ian. >> > > > -- Thanks! Yijing