> -----Original Message----- > From: Laszlo Ersek [mailto:ler...@redhat.com] > Sent: May-30-17 11:50 AM > To: Vladimir Olovyannikov; edk2-devel@lists.01.org > Cc: Ard Biesheuvel > Subject: Re: [edk2] Using a generic PciHostBridgeDxe driver for a > multi-PCIe- > domain platform > > On 05/30/17 20:32, Laszlo Ersek wrote: > > On 05/30/17 18:23, Vladimir Olovyannikov wrote: > >> Hi, > >> > >> I've started PCIe stack implementation design for an armv8 aarch64 > >> platform. > >> The platform's PCIe represents several host bridges, and each > >> hostbridge has one rootbridge. > >> They do not share any resources between each other. > >> Looking into the PciHostBridgeDxe implementation I can see that it > >> supports only one hostbridge, and there is a comment: > >> // Most systems in the world including complex servers have only one > >> Host Bridge. > >> > >> So in my case should I create my own PciHostBridgeDxe driver > >> supporting multiple hostbridges and do not use the Industry standard > driver? > >> I am very new to it, and will appreciate any help or idea. > > > > I think you can use PciHostBridgeDxe on this platform: > > > > - Implement a PciHostBridgeLib instance (see > > <MdeModulePkg/Include/Library/PciHostBridgeLib.h>) that returns > > PCI_ROOT_BRIDGE objects with different Segment fields, from > > PciHostBridgeGetRootBridges(). > > > > - Implement a PciSegmentLib instance (see > > <MdePkg/Include/Library/PciSegmentLib.h>) that routes the config space > > addresses, encoded by the PCI_SEGMENT_LIB_ADDRESS() macro, > according > > to your platform. > > > > PciHostBridgeDxe and PciBusDxe should "just work" atop. To my > > understanding, PciBusDxe delegates all config space accesses to > > PciHostBridgeDxe, via EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL. And > > PciHostBridgeDxe delegates all config space accesses to the platform's > > PciSegmentLib. > > A small addition. Assuming the general case, i.e. when you have a > different > number of root bridges on each of several host bridges, you still have to > number all those root bridges incrementally, in a curious, flat address > space. > And that address space is the PcieRoot(N) device path node that is > supposed > to start the "DevicePath" member of each PCI_ROOT_BRIDGE object that > you return from PciHostBridgeGetRootBridges(). > > You can read about the PcieRoot() devpath node in the UEFI 2.6 spec. > Basically, you have > > ACPI_HID_DEVICE_PATH.Header = <fill in as usual>; > ACPI_HID_DEVICE_PATH.HID = EFI_PNP_ID (0x0a08); > ACPI_HID_DEVICE_PATH.UID = <fill in incrementally across host bridges>; > > The UID values used in these devpath nodes should preferably match the > UID values of the corresponding PCI Express Root Bridge objects > (=PNP0A08) that you expose in your ACPI tables (DSDT and/or SSDT). Thanks for explanation Laszlo, In my case every hostbridge has exactly one rootbridge. I will follow your advice and will create SegmentPciLib and platform's PciHostBridgeLib. So basically my PciHostBridgeLib should treat hostbridges as rootbridges with different segments in this case? > > Thanks > Laszlo
Thank you, Vladimir _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
