If anyone has register maps or links to them for any pcie device, please list them here.
Intel nic controllers
NVMe SSD's
other
Using pciconf and the reg maps can help diagnose issues.
Ref: https://www.siberoloji.com/how-to-check-hardware-details-with-pciconf-and-usbconfig-on-freebsd/
I found what looks like some reg maps (recent work) done by a git user, covers most of the 200 series.
I need to decipher it, but looks good.
https://github.com/zarfld/intel-ethernet-regs/tree/a024f6d8d24b540600914a22c825b2c1980047af
devices --> gen has the h files that holds the register settings.