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* [pci] Separate permission to probe buses from bus:dev.fn range discoveryMichael Brown2024-08-151-0/+10
| | | | | | | | | | | | | | | | | The UEFI device model requires us to not probe the PCI bus directly, but instead to wait to be offered the opportunity to drive devices via our driver service binding handle. We currently inhibit PCI bus probing by having pci_discover() return an empty range when using the EFI PCI I/O API. This has the unwanted side effect that scanning the bus manually using the "pciscan" command will also fail to discover any devices. Separate out the concept of being allowed to probe PCI buses from the mechanism for discovering PCI bus:dev.fn address ranges, so that this limitation may be removed. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [pci] Cache ECAM mapping errorsMichael Brown2023-11-021-0/+2
| | | | | | | | | When an error occurs during ECAM configuration space mapping, preserve the error within the existing cached mapping (instead of invalidating the cached mapping) in order to avoid flooding the debug log with repeated identical mapping errors. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [pci] Select PCI I/O API at runtime for cloud imagesMichael Brown2022-09-181-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pretty much all physical machines and off-the-shelf virtual machines will provide a functional PCI BIOS. We therefore default to using only the PCI BIOS, with no fallback to an alternative mechanism if the PCI BIOS fails. AWS EC2 provides the opportunity to experience some exceptions to this rule. For example, the t3a.nano instances in eu-west-1 have no functional PCI BIOS at all. As of commit 83516ba ("[cloud] Use PCIAPI_DIRECT for cloud images") we therefore use direct Type 1 configuration space accesses in the images built and published for use in the cloud. Recent experience has discovered yet more variation in AWS EC2 instances. For example, some of the metal instance types have multiple PCI host bridges and the direct Type 1 accesses therefore see only a subset of the PCI devices. Attempt to accommodate future such variations by making the PCI I/O API selectable at runtime and choosing ECAM (if available), falling back to the PCI BIOS (if available), then finally falling back to direct Type 1 accesses. This is implemented as a dedicated PCIAPI_CLOUD API, rather than by having the PCI core select a suitable API at runtime (as was done for timers in commit 302f1ee ("[time] Allow timer to be selected at runtime"). The common case will remain that only the PCI BIOS API is required, and we would prefer to retain the optimisations that come from inlining the configuration space accesses in this common case. Cloud images are (at present) disk images rather than ROM images, and so the increased code size required for this design approach in the PCIAPI_CLOUD case is acceptable. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [pci] Add support for the Enhanced Configuration Access Mechanism (ECAM)Michael Brown2022-09-161-0/+55
The ACPI MCFG table describes a direct mapping of PCI configuration space into MMIO space. This mapping allows access to extended configuration space (up to 4096 bytes) and also provides for the existence of multiple host bridges. Add support for the ECAM mechanism described by the ACPI MCFG table, as a selectable PCI I/O API alongside the existing PCI BIOS and Type 1 mechanisms. Signed-off-by: Michael Brown <mcb30@ipxe.org>