Installation guide

68 Appendix C. Troubleshooting Your Installation of Red Hat Enterprise Linux

Once the boot loader screen has returned, type b to boot the system.

Once you have booted into single user mode and have access to the # prompt, you must type passwd

root, which allows you to enter a new password for root. At this point you can type shutdown -r

now to reboot the system with the new root password.

If you cannot remember your user account password, you must become root. To become root, type su

- and enter your root password when prompted. Then, type passwd <username>. This allows you

to enter a new password for the speciﬁed user account.

If the graphical login screen does not appear, check your hardware for compatibility issues. The Hard-

ware Compatibility List can be found at:

http://hardware.redhat.com/hcl/

C.4.6. Is Your RAM Not Being Recognized?

Sometimes, the kernel does not recognize all of your memory (RAM). You can check this with the

cat /proc/meminfo command.

Verify that the displayed quantity is the same as the known amount of RAM in your system. If they

are not equal, add the following line to the /boot/grub/grub.conf:

mem=xxM

Replace xx with the amount of RAM you have in megabytes.

In /boot/grub/grub.conf, the above example would look similar to the following:

#NOTICE: You have a /boot partition. This means that

# all kernel paths are relative to /boot/

default=0

timeout=30

splashimage=(hd0,0)/grub/splash.xpm.gz

title Red Hat Enterprise Linux (2.6.9-1.641_EL)

root (hd0,0)

kernel /vmlinuz-2.6.9-1.641_EL ro root=/dev/hda3 mem=128M

Once you reboot, the changes made to grub.conf are reﬂected on your system.

Once you have loaded the GRUB boot screen, type e for edit. You are presented with a list of items

in the conﬁguration ﬁle for the boot label you have selected.

Choose the line that starts with kernel and type e to edit this boot entry.

At the end of the kernel line, add

mem=xxM

where xx equals the amount of RAM in your system.

Press [Enter] to exit edit mode.

Once the boot loader screen has returned, type b to boot the system.

Itanium users must enter boot commands with elilo followed by the boot command.

Remember to replace xx with the amount of RAM in your system. Press [Enter] to boot.