sysfs

• The bus, device, drivers, etc. structures are internal to the kernel

• The sysfs virtual filesystem offers a mechanism to export such information to userspace

• Used for example by udev to provide automatic module loading, firmware loading, device file creation, etc.

• sysfs is usually mounted in /sys

• /sys/bus/ contains the list of buses
• /sys/devices/ contains the list of devices
• /sys/class enumerates devices by class (net, input, block...), whatever the bus they are connected to. Very useful!
• Take your time to explore /sys on your workstation.