6a744d40d0
Add a library class, and a BASE lib instance, that are layered on top of PciCapLib, and allow clients to plug a PciSegmentLib backend into PciCapLib, for config space access. (Side note: The "MaxDomain" parameter is provided because, in practice, platforms exist where a PCI Express device may show up on a root bridge such that the root bridge doesn't support access to extended config space. Earlier the same issue was handled for MdeModulePkg/PciHostBridgeDxe in commit014b472053. However, that solution does not apply to the PciSegmentLib class, because: (1) The config space accessor functions of the PciSegmentLib class, such as PciSegmentReadBuffer(), have no way of informing the caller whether access to extended config space actually succeeds. (For example, in the UefiPciSegmentLibPciRootBridgeIo instace, which could in theory benefit from commit014b472053, the EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL.Pci.Read() status code is explicitly ignored, because there's no way for the lib instance to propagate it to the PciSegmentLib caller. If the EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL.Pci.Read() call fails, then DxePciSegmentLibPciRootBridgeIoReadWorker() returns Data with indeterminate value.) (2) There is no *general* way for any firmware platform to provide, or use, a PciSegmentLib instance in which access to extended config space always succeeds. In brief, on a platform where config space may be limited to 256 bytes, access to extended config space through PciSegmentLib may invoke undefined behavior; therefore PciCapPciSegmentLib must give platforms a way to prevent such access.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
36 lines
995 B
INI
36 lines
995 B
INI
## @file
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# Plug a PciSegmentLib backend into PciCapLib, for config space access.
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#
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# Copyright (C) 2018, Red Hat, Inc.
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#
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# This program and the accompanying materials are licensed and made available
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# under the terms and conditions of the BSD License which accompanies this
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# distribution. The full text of the license may be found at
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# http://opensource.org/licenses/bsd-license.php
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#
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# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
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# WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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##
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[Defines]
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INF_VERSION = 1.27
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BASE_NAME = BasePciCapPciSegmentLib
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FILE_GUID = ED011855-AA31-43B9-ACC0-BF45A05C5985
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MODULE_TYPE = BASE
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VERSION_STRING = 1.0
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LIBRARY_CLASS = PciCapPciSegmentLib
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[Sources]
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BasePciCapPciSegmentLib.h
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BasePciCapPciSegmentLib.c
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[Packages]
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MdePkg/MdePkg.dec
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OvmfPkg/OvmfPkg.dec
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[LibraryClasses]
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BaseLib
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DebugLib
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MemoryAllocationLib
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PciSegmentLib
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