# Linux Kernel Module Cheat

##### 23.6.1.5. PCI BFD

`lspci -k` shows something like:

    00:04.0 Class 00ff: 1234:11e8 lkmc_pci

Meaning of the first numbers:

    <8:bus>:<5:device>.<3:function>

Often abbreviated to BDF.

- bus: groups PCI slots

- device: maps to one slot

- function: https://stackoverflow.com/questions/19223394/what-is-the-function-number-in-pci/44735372#44735372

Sometimes a fourth number is also added, e.g.:

    0000:00:04.0

TODO is that the domain?

Class: pure magic: https://www-s.acm.illinois.edu/sigops/2007/roll_your_own/7.c.1.html TODO: does it have any side effects? Set in the edu device at:

    k->class_id = PCI_CLASS_OTHERS