Re: Using a generic PciHostBridgeDxe driver for a multi-PCIe-domain platform

[Laszlo Ersek <lersek@redhat.com>]

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.

Thanks,
Laszlo