On Wed, Feb 08, 2017 at 10:39:55AM +1100, Andrew Donnellan wrote: >On 08/02/17 10:21, Gavin Shan wrote: >>On Tue, Feb 07, 2017 at 10:12:48PM +1100, Michael Ellerman wrote: >>>Andrew Donnellan <[email protected]> writes: >> >>.../... >> >>>>The effect of this patch is to copy the memory resources from the *real* >>>>PHB to the vPHB, as given through the device tree. It shouldn't have any >>>>practical effect other than squashing this message. >>> >>>It sounds a bit backward to me. If we don't need the resources then >>>why have them? >>> >>>If we have code that thinks that's an error, than maybe that's what >>>needs fixing, or special casing for the vPHB? >>> >> >>Yeah, vPHB is a special case. There are basically two stages in PCI >>enumeration: >>probing and then resource assignment. vPHB is different from *real* PHB as the >>resource assignment is skipped on it. So vPHB doesn't need any resources to be >>populated. However, there is a check in probing stage and it's where the >>warning >>message comes from. >> >> drivers/misc/cxl/vphb.c::cxl_pci_vphb_add() >> arch/powerpc/kernel/pci-common.c::pcibios_scan_phb() >> pcibios_setup_phb_resources() >> >> static void pcibios_setup_phb_resources(struct pci_controller *hose, >> struct list_head *resources) >> { >> : >> for (i = 0; i < 3; ++i) { >> res = &hose->mem_resources[i]; >> if (!res->flags) { >> if (i == 0) >> printk(KERN_ERR "PCI: Memory resource 0 not set for " >> "host bridge %s (domain %d)\n", >> hose->dn->full_name, hose->global_number); >> continue; >> } >> : >> } >> >>Alternatively, we can replace prink(KERN_ERR) with pr_debug(). It's going to >>affect all PHBs including the real ones. Andrew and Michael, what do you >>think? :-) > >In what other circumstances do we get this error printed on real PHBs? >
When hose->mem_resources[0] isn't built from PHB's device-tree node. It means the device-tree node's "ranges" isn't populated correctly by loader and it should be very rare ... I never saw it before. Thanks, Gavin
