Chapter 7.9. Device and Module Handling on an LFS System

 root:/# modinfo

Usage: modinfo [-0][-F field][-k kernelversion][-b basedir]  module...
 Prints out the information about one or more module(s).
 If a fieldname is given, just print out that field (or nothing if not found).
 Otherwise, print all information out in a readable form
 If -0 is given, separate with nul, not newline.
 If -b is given, use an image of the module tree.

root:/# ls -l sys/bus

total 0
drwxr-xr-x 4 root root 0 Jun 17 10:05 ac97
drwxr-xr-x 4 root root 0 Jun 17 10:05 acpi
drwxr-xr-x 4 root root 0 Jun 17 10:05 gameport
drwxr-xr-x 4 root root 0 Jun 17 10:05 i2c
drwxr-xr-x 4 root root 0 Jun 17 10:05 isa
drwxr-xr-x 5 root root 0 Jun 17 10:05 pci
drwxr-xr-x 4 root root 0 Jun 17 10:05 pci_express
drwxr-xr-x 4 root root 0 Jun 17 10:05 platform
drwxr-xr-x 4 root root 0 Jun 17 10:05 pnp
drwxr-xr-x 4 root root 0 Jun 17 10:05 scsi
drwxr-xr-x 4 root root 0 Jun 17 10:05 serio
drwxr-xr-x 4 root root 0 Jun 17 10:05 spi
drwxr-xr-x 4 root root 0 Jun 17 10:05 usb
drwxr-xr-x 4 root root 0 Jun 17 10:05 virtio

Each of thos directories has the same set of files i.e. Ac97

drwxr-xr-x 2 root root    0 Jun 17 10:07 devices
drwxr-xr-x 2 root root    0 Jun 17 10:07 drivers
-rw-r--r-- 1 root root 4096 Jun 17 10:07 drivers_autoprobe
--w------- 1 root root 4096 Jun 17 10:07 drivers_probe
--w------- 1 root root 4096 Jun 17 10:07 uevent

Under these directories, there are more. I have cat'd the entire list to a file. (ls -l sys/bus/*/*/* > sys_bus_before.list)

 Maybe some day it will make sense. What I do not understand is how they got there. I only looked after I had typed modprobe which is the same time as the time stamp on the files. I am going to try and log out of chroot environment and log in again to see if they are still there. So they are permanent. It must have been something I did today because I just started this morning.

I do not understand what I have to do in this chapter.

I'll try the reading recomendations.

Userspace Implementation:  This is a useful defintion. "A device file is how a user program can access a specific hardware device or function." I never thought of the "hda" in /dev/hda as a file, but apparently it is and it "represents the first IDE drive of the system". Although I am used to seeing it with a number as well. The way Linux (or unix) is sold is via this "everything is a file concept.  I made a listing of the /dev directory and saved a copy. One of the lines for LFS is this one, /dev/sdb6

brw-rw---- 1 root daemon   8,  22 Jun 17 10:24 sdb6

I notice the b at the beginning and the word daemon as the group. This determines the properties of the file? Name has to match type of device, and are listed in  Device List

Wow, I remember having this problem years ago (probably with kernel 2.4) "If the user rearranges the USB topology, perhaps adding a USB hub in order to support more USB devices in the system, the USB probing order of the printers might change the next time the computer is booted, reversing the assignment of the different minor number to the two printers"

There is too much to understand in this article, so I am going to move on. If something does not work, I'll have to come back.