In kernel parameter, we can see:


nommconf        [X86] Disable use of MMCONFIG for PCI Configuration

What is this feature? When it will be needed?

1 Answer 1


It's not a feature, it's a flag which disables certain functionality in the kernel. MMCONFIG is memory mapped PCI configuration registers, aka extended PCIe configuration. In case you don't want the kernel to read these registers you disable it. Some devices in the past used to have issues when reading the registers.

Some relevant info: https://lwn.net/Articles/263288/

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