Feature Request: view / edit PCie payload configs and enable MSI-X for double message capacity

[brunogm0]

My Radeon iGPU uses MSI-X but my Radeon dGPU only MSI; MSI-X would benefit dGPU at least in double capacity per message. Also MSI-X even with one interrupt could help other devices like sata or ethernet; Then max/current payload sizes could be improved since devices like Realtek GbE limits unnecessarily to 128bytes;
Maybe one has to change how devices are nested from each root complex to optimize. (like dedicated root complex to Realtek GbE , so other devices can use bigger payload )

Proposal:

1. Show PCIe max & current payload size; Allow changes or at least inform PCIe config bottlenecks;
2. Allow MSI-X since double message size vs MSI could help in lower overhead + latency;

Thanks ,

[spddl]

I don't know if I understand you correctly, I read the properties of each device with SetupDiEnumDeviceInfo and SetupDiGetDevicePropertyW.
I don't think it's useful to set MSI-X for everything if the device or driver doesn't support it.

[brunogm0]

"MSI-X for everything if the device or driver doesn't support it. " yeah that's not it.

I cannot find a exact documentation on the diff MSI and MSI-X, and its was ambiguous in the case that a function uses only one message vector. "Allow MSI-X" was based on my read that for only one interrupt could add some advantages (message size? ) and be compatible. I could not find better docs and maybe its not compatible. The diff advantages of MSI-X over MSI besides the expansion from 32 to 2048 max vectors is not clearly documented.

My main feature request is to show PCIe capabilities that are important for bus efficiency like payloads and read-request sizes; And allow overrides in the ones that are RW; On Linux one can use lspci and setpci. But SetPCI dont have easy setters for basic info lspci dumps.

[lextra2]

You cannot force any device that doesn't come with MSI-X support into MSI-X.

Currently, there are no dedicated GPUs that support MSI-X.

I cannot find a exact documentation

Here you go