C.1.1. x86 Specific Instructions — Are You Unable to Boot from the CD-ROM?

	Note
	There are a few cases where the system BIOS does not allow the Red Hat Enterprise Linux CD-ROM to boot because of the size of the boot image on the CD-ROM itself. In cases such as these, a boot diskette should be made to boot the installation program. Once booted, the CD-ROMs work properly for the installation.

If you cannot boot from your Red Hat Enterprise Linux CD-ROM, you have two options:

1. Change your BIOS so that booting from the CD-ROM is recognized first in the boot order

2. Boot using a boot diskette you have created

To change your BIOS, refer to your system manual for the correct keyboard combination that allows you to access your BIOS, or you can read the key sequence needed while the system begins to boot (assuming it is displayed).

To create a boot diskette, follow the instructions in Section 2.5.3 Making an Installation Boot Diskette.

To boot Red Hat Enterprise Linux using a boot diskette, insert the diskette you have created into your diskette drive and then boot/reboot your computer. Make sure that your BIOS is set to use the diskette or removable diskette to boot.

C.1.2. x86 Specific Instructions — Are You Unable to Boot from a Boot Diskette?

If you cannot boot from a boot diskette, you have two options:

1. Change your BIOS so that booting from the boot diskette is recognized first in the boot order

2. Boot using an updated boot diskette image

To change your BIOS, refer to your system manual for the correct keyboard combination that allows you to access your BIOS, or you can read the key sequence needed while the system begins to boot (assuming it is displayed).

To find an updated boot diskette image, check the online errata at

http://www.redhat.com/support/errata/

and follow the instructions in Section 2.5.3 Making an Installation Boot Diskette to make an updated boot diskette for your system.

C.1.3. Are You Unable to Boot With Your RAID Card?

If you have performed an installation and cannot boot your system properly, you may need to reinstall and create your partitions differently.

Some BIOSes do not support booting from RAID cards. At the end of an installation, a text-based screen showing the boot loader prompt (for example, GRUB:) and a flashing cursor may be all that appears. If this is the case, you will need to repartition your system.

Whether you choose automatic or manual partitioning, you will need to install your /boot partition outside of the RAID array, such as on a separate hard drive. An internal hard drive is necessary to use for partition creation with problematic RAID cards.

You must also install your preferred boot loader (GRUB or LILO) outside of the RAID array — not on the MBR. The boot loader should be installed on the MBR of the same drive as the /boot partition was created.

Once these changes have been made, you should be able to finish your installation and boot the system properly.

C.1.4. Is Your System Displaying Signal 11 Errors?

A signal 11 error, commonly know as a segmentation fault, means that the program accessed a memory location that was not assigned.

If you receive a fatal signal 11 error during your installation, it is probably due to a hardware error in memory on your system's bus. A hardware error in memory can be caused by problems in executables or with the system's hardware. Like other operating systems, Red Hat Enterprise Linux places its own demands on your system's hardware. Some of this hardware may not be able to meet those demands, even if they work properly under another OS.

Review if you have the latest installation and supplemental boot diskettes from Red Hat. Review the online errata to check if newer versions are available. If the latest images still fail, it may be due to a problem with your hardware. Commonly, these errors are in your memory or CPU-cache. A possible solution for this error is turning off the CPU-cache in the BIOS. You could also try to swap your memory around in the motherboard slots to check if the problem is either slot or memory related.

You can also try running the installation with only 256 MB of memory. This can be done by booting the installation program with the mem=256M boot option. To try this option, at the installation boot prompt, type:

mem=xxxM

where xxx should be replaced with the amount of memory in megabytes.

This command allows you to override the amount of memory the kernel detects for the machine. This may be needed for some older systems where only 16MB is detected by the installation program (but more RAM is present in the system), and for some new machines where the video card shares the video memory with the main memory.

Another option is to perform a media check on your installation CD-ROMs. To test the checksum integrity of an ISO image, at the installation boot prompt, type:

linux mediacheck

This command works with the CD, DVD, hard drive ISO, and NFS ISO installation methods.

For more information concerning signal 11 errors, refer to:

http://www.bitwizard.nl/sig11/