# The first line names the menu item "linux".
# The second line specifies that the kernel is located on the first physical hard 75
# drive (hd0), the second partition (2), the boot image is the file /boot/vmlinux
# Also on the second line, the following options are passed to the kernel:
# root=/dev/hda3 (i.e., make the root partition the 3d partition on the first hard drive (hda) ),
# mem=64M (i.e., use 64 megabytes of physical memory).
Good documentation for GRUB is available using info grub
4.1.1 Linux cannot detect all my memory
If you have more than 64 megabytes of physical memory, Linux kernel ver. 2.0.36 or lower will use, by default, only the first 64 MB. To see how much memory Linux uses on your system, type: cat /proc/meminfo
or
free
You can check your version of Linux kernel with:
uname -a
The last popular kernel with the "memory problem", 2.0.36, comes with RedHat 5.2. My RedHat 6.0 came with kernel 2.2.5-15 so it does not have the "memory problem" any more.
To get more than 64 MB memory recognized on RH5.2, you have to edit (as root) the file
/etc/lilo.conf, and add a line like this just before your first "image=" statement: append="mem=80M"
If you have an amount of memory different than 80 MB, adjust the above line. For any changes in /etc/lilo.conf to take effect, you *must* re-run the program
lilo
(watch if it runs without errors) and reboot. After the reboot, you can check if your adjustment worked using either of these two commands:
cat /proc/meminfo
free
For testing purposes, or if you are having problems, the option of specifying the amount of memory at the LILO prompt is useful:
[type at LILO prompt during bootup] linux "mem=16M"
Occasionally, I hear the advice to skip the upper few megabytes if you have problems enabling all your memory, or the machine locks up. E.g., enable only 78 out of your 80 MB. This is apparently the case for some SCSI controllers that use the very upper chunk of the main memory.
Take it for what it’s worth.
Occasionally on some systems, Linux recognizes only 16 MB of memory. This is usually linked to the setting "memory hole at 15-16 MB" enabled in the BIOS setup (the solution is to disable this BIOS setting). It is probably a good idea to disable all "advanced" features in your BIOS
setup anyway (for example, the BIOS virus detection seems to be a common source of problems
).
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Mixture of memory chips with different timings can also lead to memory recognition problems or to system crashes (the solution is to replace the memory chips so that the timing of all memory chips is the same).
4.1.2 LILO displays only LI (or LIL) and hangs
I quote from my good handbook "Red Hat Linux Unleashed" by Kamran Hussain, Timothy Parker, et al., published by SAMS Publishing:
"When LILO loads itself, it displays the word LILO. Each letter is printed before or after performing some specific action. If LILO fails at some point, the letters printed so far can be used to identify the problem. [...]
LI [...] This is caused either by geometry mismatch or by moving /etc/lilo/boot.b without running the map installer.
LIL [...] This is typically caused by media failure or geometry mismatch."
The geometry means the number of sectors/heads/cylinders used in the hard drive configuration of your BIOS. Hope this helps!
It is a very good idea to have a handbook for Linux or at least a general UNIX handbook.
Handbooks for Windows are useless, handbooks for Linux are great! "Red Hat Linux Unleashed" is a very good handbook but I am sure there are many other equally good ones.
With a LILO error like above, you can boot your machine using a Linux or DOS boot floppy.
There seems to be several general possibilities to correct such a LILO error, depending on what is wrong:
1. If LILO simply got corrupted (does not seem very common), you can remove and re-install it.
You can remove LILO by running under Linux:
lilo -u /dev/hda
or, under DOS:
FDISK/MBR