mirror of https://github.com/acidanthera/audk.git
3f5b1b9132
Consume the host-provided specification of PCI host bridges if available. Using the DxeHardwareInfoLib, populate a list of hardware descriptors based on the content of the "hardware-info" fw-cfg file, if provided. In the affirmative case, use the resources and attributes specified by the hypervisor for each Host Bridge to create the RootBridge elements. In Ovmf platforms, the host can provide the specification of non-discoverable hardware resources like PCI host bridges. If the proper fw-cfg file is found, parse the contents provided by the host into a linked list by using the Hardware Info library. Then, using the list of PCI host bridges' descriptions, populate the PCI_ROOT_BRIDGES array with the resources and attributes specified by the host. If the file is not provided or no Host Bridge is found in it, fold back to the legacy method based on pre-defined apertures and rules. In some use cases, the host requires additional control over the hardware resources' configurations in the guest for performance and discoverability reasons. For instance, to disclose information about the PCI hierarchy to the guest so that this can profit from optimized accesses. In this case, the host can decide to describe multiple PCI Host Bridges and provide a specific set of resources (e.g. MMIO apertures) so that the guest uses the values provided. Using the provided values may entitle the guest to added performance, for example by using specific MMIO mappings that can enable peer-to-peer communication across the PCI hierarchy or by allocating memory closer to a device for faster DMA transactions. Cc: Alexander Graf <graf@amazon.de> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Nicolas Ojeda Leon <ncoleon@amazon.com> |
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| .. | ||
| PciHostBridgeUtilityLib.c | ||
| PciHostBridgeUtilityLib.inf | ||