3.3.2. /proc/bus/

3.3.2. /proc/bus/

This directory contains information specific to the various buses available on the system. For example, on a standard system containing PCI and USB buses, current data on each of these buses is available within a subdirectory within /proc/bus/ by the same name, such as /proc/bus/pci/.

The subdirectories and files available within /proc/bus/ vary depending on the devices connected to the system. However, each bus type has at least one directory. Within these bus directories are normally at least one subdirectory with a numerical name, such as 001, which contain binary files.

For example, the /proc/bus/usb/ subdirectory contains files that track the various devices on any USB buses, as well as the drivers required for them. The following is a sample listing of a /proc/bus/usb/ directory:

total 0 dr-xr-xr-x    1 root     root            0 May  3 16:25 001 
-r--r--r--    1 root     root            0 May  3 16:25 devices 
-r--r--r--    1 root     root            0 May  3 16:25 drivers

The /proc/bus/usb/001/ directory contains all devices on the first USB bus and the devices file identifies the USB root hub on the motherboard.

The following is a example of a /proc/bus/usb/devices file:

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2 
B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0 
D:  Ver= 1.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1 
P:  Vendor=0000 ProdID=0000 Rev= 0.00 
S:  Product=USB UHCI Root Hub 
S:  SerialNumber=d400 
C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr=  0mA 
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub 
E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=255ms

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