10.4.6. 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 Client (2.6.27.19-170.2.35.el5.i686)
root (hd0,1)
kernel /vmlinuz-2.6.27.19-170.2.35.fc10.i686 ro root=UUID=04a07c13-e6bf-6d5a-b207-002689545705 mem=1024M
initrd /initrd-2.6.27.19-170.2.35.fc10.i686.img

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.

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