> On 17 Jul 2020, at 16:41, Roger Pau Monné <roger....@citrix.com> wrote: > > On Fri, Jul 17, 2020 at 02:34:55PM +0000, Bertrand Marquis wrote: >> >> >>> On 17 Jul 2020, at 16:06, Jan Beulich <jbeul...@suse.com> wrote: >>> >>> On 17.07.2020 15:59, Bertrand Marquis wrote: >>>> >>>> >>>>> On 17 Jul 2020, at 15:19, Jan Beulich <jbeul...@suse.com> wrote: >>>>> >>>>> On 17.07.2020 15:14, Bertrand Marquis wrote: >>>>>>> On 17 Jul 2020, at 10:10, Jan Beulich <jbeul...@suse.com> wrote: >>>>>>> On 16.07.2020 19:10, Rahul Singh wrote: >>>>>>>> # Emulated PCI device tree node in libxl: >>>>>>>> >>>>>>>> Libxl is creating a virtual PCI device tree node in the device tree to >>>>>>>> enable the guest OS to discover the virtual PCI during guest boot. We >>>>>>>> introduced the new config option [vpci="pci_ecam"] for guests. When >>>>>>>> this config option is enabled in a guest configuration, a PCI device >>>>>>>> tree node will be created in the guest device tree. >>>>>>> >>>>>>> I support Stefano's suggestion for this to be an optional thing, i.e. >>>>>>> there to be no need for it when there are PCI devices assigned to the >>>>>>> guest anyway. I also wonder about the pci_ prefix here - isn't >>>>>>> vpci="ecam" as unambiguous? >>>>>> >>>>>> This could be a problem as we need to know that this is required for a >>>>>> guest upfront so that PCI devices can be assigned after using xl. >>>>> >>>>> I'm afraid I don't understand: When there are no PCI device that get >>>>> handed to a guest when it gets created, but it is supposed to be able >>>>> to have some assigned while already running, then we agree the option >>>>> is needed (afaict). When PCI devices get handed to the guest while it >>>>> gets constructed, where's the problem to infer this option from the >>>>> presence of PCI devices in the guest configuration? >>>> >>>> If the user wants to use xl pci-attach to attach in runtime a device to a >>>> guest, this guest must have a VPCI bus (even with no devices). >>>> If we do not have the vpci parameter in the configuration this use case >>>> will not work anymore. >>> >>> That's what everyone looks to agree with. Yet why is the parameter needed >>> when there _are_ PCI devices anyway? That's the "optional" that Stefano >>> was suggesting, aiui. >> >> I agree in this case the parameter could be optional and only required if >> not PCI device is assigned directly in the guest configuration. > > Where will the ECAM region(s) appear on the guest physmap? > > Are you going to re-use the same locations as on the physical > hardware, or will they appear somewhere else?
We will add some new definitions for the ECAM regions in the guest physmap declared in xen (include/asm-arm/config.h) So they will appear at a different address then the hardware. Bertrand > > Roger.
