Linux Driver Subsystem

from https://www.kernel.org/doc/html/latest/driver-api/driver-model/bus.html Every driver in the Linux kernel is associated with a bus type, which defines the interface between the kernel and the hardware devices. A bus is a channel between the processor and one or more devices. For the purposes of the device model, all devices are connected via a bus, even if it is an internal, virtual, “platform” bus. Buses can plug into each other. A USB controller is usually a PCI device, for example. Each bus gets its own directory , along with two default directory ```s @Anurag252 ➜ /workspaces/codespaces-blank $ ls /sys/bus acpi cpu gpio mdio_bus node platform serio vmbus auxiliary dax hid memory nvmem pnp soc vme clockevents edac i2c memory_tiering pci rapidio spi workqueue clocksource eisa isa mipi-dsi pci-epf scsi usb container event_source machinecheck nd pci_express serial-base virtio ls /sys/bus/pci devices drivers drivers_autoprobe drivers_probe rescan resource_alignment slots uevent ``` Each registered driver gets a directory in bus's driver directory. ```s @Anurag252 ➜ /workspaces/codespaces-blank $ ls /sys/bus/pci/drivers 8250_mid ata_generic intel_scu mlx5_core pata_sis serial xhci_hcd agpgart-intel ata_piix iosf_mbi_pci nvme pcieport shpchp agpgart-via hyperv_drm mana pata_acpi pwm-lpss virtio-pci ``` also each device that gets discovered on bus gets a directory in devices folder ``` @Anurag252 ➜ /workspaces/codespaces-blank $ ls /sys/bus/pci/devices/ 0000:00:00.0 0000:00:07.0 0000:00:07.1 0000:00:07.3 0000:00:08.0 2614:00:02.0 ```