On 9/3/19 8:20 PM, Igor Druzhinin wrote: > If MCFG area is not reserved in E820, Xen by default will defer its usage > until Dom0 registers it explicitly after ACPI parser recognizes it as > a reserved resource in DSDT. Having it reserved in E820 is not > mandatory according to "PCI Firmware Specification, rev 3.2" (par. 4.1.2) > and firmware is free to keep a hole E820 in that place. Xen doesn't know > what exactly is inside this hole since it lacks full ACPI view of the > platform therefore it's potentially harmful to access MCFG region > without additional checks as some machines are known to provide > inconsistent information on the size of the region. > > Now xen_mcfg_late() runs after acpi_init() which is too late as some basic > PCI enumeration starts exactly there. Trying to register a device prior > to MCFG reservation causes multiple problems with PCIe extended > capability initializations in Xen (e.g. SR-IOV VF BAR sizing). There are > no convenient hooks for us to subscribe to so try to register MCFG > areas earlier upon the first invocation of xen_add_device().
Where is MCFG parsed? pci_arch_init()? -boris > Keep the > existing initcall in case information of MCFG areas is updated later > in acpi_init(). > _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
