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| -rw-r--r-- | Documentation/releases/coreboot-4.13-relnotes.md | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/releases/coreboot-4.13-relnotes.md b/Documentation/releases/coreboot-4.13-relnotes.md index 94e93bb75b..1d8839fea2 100644 --- a/Documentation/releases/coreboot-4.13-relnotes.md +++ b/Documentation/releases/coreboot-4.13-relnotes.md @@ -13,4 +13,19 @@ Update this document with changes that should be in the release notes. Significant changes ------------------- +### Hidden PCI devices + +This new functionality takes advantage of the existing 'hidden' keyword in the +devicetree. Since no existing boards were using the keyword, its usage was +repurposed to make dealing with some unique PCI devices easier. The particular +case here is Intel's PMC (Power Management Controller). During the FSP-S run, +the PMC device is made hidden, meaning that its config space looks as if there +is no device there (Vendor ID reads as 0xFFFF_FFFF). However, the device does +have fixed resources, both MMIO and I/O. These were previously recorded in +different places (MMIO was typically an SA fixed resource, and I/O was treated +as an LPC resource). With this change, when a device in the tree is marked as +'hidden', it is not probed (`pci_probe_dev()`) but rather assumed to exist so +that its resources can be placed in a more natural location. This also adds the +ability for the device to participate in SSDT generation. + ### Add significant changes here |