Moving In...

Booting Linux

1. Create a boot disk

   [root@bluenote /root]# dd if=/vmlinuz of=/dev/fd0
   

2. Install LILO (Linux Linker LOader)

   [root@bluenote /root]# /sbin/lilo -C /etc/lilo.conf
   

   A sample /etc/lilo.conf file:

   compact
   boot=/dev/hda
   map=/boot/map
   install=/boot/boot.b
   prompt
   timeout=100
   other=/dev/hda1
   	label=dos
   	table=/dev/hda
   image=/vmlinuz
   	label=develop
   	root=/dev/sda3
   	password=goaway
   	restricted
   	read-only
   image=/vmlinuz
   	label=linux
   	root=/dev/hda2
   	read-only
   

3. Preserving your master boot record before installing LILO - from the LILO documentation.

   The first 446 (0x1BE) bytes of the MBR are used by the loader program. They are followed by the partition table, with a length of 64 (0x40) bytes. The last two bytes contain a magic number that is sometimes used to verify that a given sector really is a boot sector.

   Installation:

   1. boot Linux.
   2. make a backup copy of your MBR on a floppy disk, e.g.

      dd if=/dev/hda of=/fd/MBR bs=512 count=1 
      

   3. install LILO with the boot sector on the Linux partition.
   4. install BOOTACTV as the MBR, e.g.

      dd if=bootactv.bin of=/dev/hda bs=446 count=1 
      

   5. reboot.

   Deinstallation:

   1. boot Linux.
   2. restore the old MBR, e.g.

      dd if=/MBR of=/dev/hda bs=446 count=1
      or FDISK /MBR under MS-DOS. 
      

4. rdev - query/set image root device, swap device, RAM disk size, or video mode

Rebuild the Linux Kernel

1. Distribution kernels contain many extra drivers (to facilitate working with the most systems) you may not need. Recompiling the kernel removes these drivers and shrinks the binary kernel image size.

   [root@bluenote /root]# ls -l /vmlinuz*
   -rw-r--r--   1 root     root       428938 Mar 11 19:00 vmlinuz
   -rw-r--r--   1 root     root       479309 Mar  9 19:48 vmlinuz_distribution
   

2. dmesg - print or control the kernel ring buffer. This command displays kernel messages so you won't have to write them down furiously as the system boots!
   Using dmesg I can determine the amount of free memory after the kernel loads.

   [root@bluenote /root]# dmesg | grep Memory
   Memory: 31288k/32768k available (764k kernel code, 384k reserved, 332k data)
   

3. The /proc filesystem contains many interesting human readable files that contain information about your Linux system.
   What devices are supported by this Linux kernel.

   60 18:10/home/code/sluugls/1996/apr> cat /proc/devices 
   Character devices:
    1 mem
    2 pty
    3 ttyp
    4 tty
    5 cua
    6 lp
    7 vcs
   14 sound
   21 sg
   
   Block devices:
    2 fd
    3 ide0
    8 sd
   11 sr
   

   What types of filesystems are supported by this Linux kernel.

   61 18:11/home/code/sluugls/1996/apr> cat /proc/filesystems 
           ext2
   	minix
   	msdos
   nodev   proc
   nodev   nfs
   nodev   smbfs
   	iso9660
   

   How many interrupts have been recorded by interrupt.

   62 18:12/home/code/sluugls/1996/apr> cat /proc/interrupts
     0:   221246   timer
     1:     1936   keyboard
     2:        0 + cascade
     4:     5327 + serial
     5:        2   SoundBlaster
    11:     5622 + aic7xxx
    12:       23   3c509
    13:        0   math error
    14:      494 + ide0
   

   What I/O addresses are being used.

   66 18:14/home/code/sluugls/1996/apr> cat /proc/ioports 
   0000-001f : dma1
   0020-003f : pic1
   0040-005f : timer
   0060-006f : kbd
   0070-007f : rtc
   0080-009f : dma page reg
   00a0-00bf : pic2
   00c0-00df : dma2
   00f0-00ff : npu
   01f0-01f7 : ide0
   0220-022f : SB
   0278-027f : lp
   02f8-02ff : serial(auto)
   0300-030f : 3c509
   0378-037f : lp
   03c0-03df : vga+
   03f0-03f5 : floppy
   03f6-03f6 : ide0
   03f7-03f7 : floppy DIR
   03f8-03ff : serial(auto)
   fc00-fcbe : aic7xxx
   

   A map of the system memory. This file is not taking up any disk space. DO NOT DELETE IT. Copying this file will consume disk space.

   67 18:14/home/code/sluugls/1996/apr> l /proc/kcore 
   -r--------   1 root     root     33558528 Apr 17 18:15 /proc/kcore
   

The Devices

/dev contains the files necessary for the kernel to interface with the physical computer hardware. If files are missing /dev/MAKEDEV can create them for you.

MAKEDEV is a script that will create the devices in /dev used to interface with drivers in the kernel.

Note that programs giving the error ``ENOENT: No such file or directory'' normally means that the device file is missing, whereas ``ENODEV: No such device'' normally means the kernel does not have the driver configured or loaded.

[root@bluenote /dev]# /dev/MAKEDEV -v update

/dev/null               # returns end of file
/dev/zero               # returns \0 characters
/dev/full               # simulates a full disk

Last Modified: 17 April 1996