Booting the Installation Program | The Red Hat Documentation Team

You can boot the Red Hat Linux installation program using any one of the following media (depending upon what your system can support):

Bootable CD-ROM — Your machine supports a bootable CD-ROM drive and you want to perform a local CD-ROM installation.
Local boot diskette — Your machine will not support a bootable CD-ROM and you want to install from a local CD-ROM or a hard drive.
Network boot diskette — Use a network boot diskette to install via NFS, FTP, and HTTP.
PCMCIA boot diskettes — Use PCMCIA boot diskettes when you need PCMCIA support but your machine does not support booting from the CD-ROM drive or if you need PCMCIA support in order to make use of the CD-ROM drive on your system. The PCMCIA boot diskettes can be used for all installation methods (CD-ROM, hard drive, NFS, FTP, and HTTP).

To create a boot diskette, refer to Chapter 1.

Insert the boot diskette into your computer's first diskette drive and reboot (or boot using the CD-ROM, if your computer supports booting from it). Your BIOS settings may need to be changed to allow you to boot from the diskette or CD-ROM.

Changing Your BIOS Settings

To change your BIOS settings, watch the instructions provided on your display when your computer first boots. You will see a line of text telling you to press the Del or F1 key to enter the BIOS settings. Once you have entered your BIOS setup program, find the section where you can alter your boot sequence. The default is often “C, A” or “A, C” (depending on whether you boot from your hard drive C or a diskette in drive A). Change this sequence so that the CD-ROM is first in your boot order and that C or A (whichever is your typical boot default) is second. This instructs the computer to first look at the CD-ROM drive for bootable media; if it does not find bootable media on the CD-ROM drive, it will then check your hard drive or diskette drive. Save your changes before exiting the BIOS. For more information, refer to the documentation that came with your system.

After a short delay, a screen containing the boot: prompt should appear. The screen contains information on a variety of boot options. Each boot option also has one or more help screens associated with it. To access a help screen, press the appropriate function key as listed in the line at the bottom of the screen.

As you boot the installation program, be aware of two issues:

Once you see the boot: prompt, the installation program will automatically begin if you take no action within the first minute. To disable this feature, press one of the help screen function keys.
If you press a help screen function key, there will be a slight delay while the help screen is read from the boot media.

Normally, you only need to press Enter to boot the installation program. Watch the boot messages to see if the Linux kernel detects your hardware. If your hardware is properly detected, you can continue to the next section. If it does not properly detect your hardware, you may need to restart the installation in expert mode.

Additional Boot Options

While it is easiest for a user to boot from the CD-ROM and perform a graphical installation, sometimes there are installation scenarios where booting in a different manner may be needed. This section discusses addition boot options available for Red Hat Linux.

Note

See Table 2-2 in this section for additional boot options.

If you do not wish to perform a graphical installation, you can start a text mode installation using the following boot command:
```
boot: linux text 
```
ISO images now have an md5sum embedded in them. To test the checksum integrity of an ISO image, at the installation boot prompt type:
```
boot: linux mediacheck 
```
The installation program will prompt you to insert a CD or select an ISO image to test and select OK to perform the checksum operation. This checksum operation can be performed on any Red Hat Linux CD and does not have to be performed in a specific order (for example, CD #1 does not have the be the first CD you verify). It is strongly recommended to perform this operation on any Red Hat Linux CD that was created from downloaded ISO images. This procedure works with CD-based installations and hard drive and NFS installations using ISO images.
If the installation program does not properly detect your hardware, you may need to restart the installation in expert mode. Expert mode disables most hardware probing and allows you to enter options for the drivers loaded during the installation. The initial boot messages will not contain any references to SCSI or network cards. This is normal; these devices are supported by modules that are loaded during the installation process. Enter expert mode using the following boot command:
```
boot: linux noprobe 
```
For text mode installations, use:
```
boot: linux text noprobe 
```
If you need to perform the installation in serial mode, type the following command:
```
boot: linux console=device 
```
For text mode installations, use:
```
boot: linux text console=device 
```

In the above command, device should be the device you are using (such as ttyS0 or ttyS1). For example, linux text console=ttyS0,115200n8.

Table 2-2 shows more boot-time command arguments.

Table 2-2: Boot Options
Command	What It Does
askmethod	Asks you to select the installation method you would like to use when booting from the Red Hat Linux CD-ROM.
apic	Works around a bug commonly encountered in the Intel 440GX chipset BIOS and should only be executed with the installation program kernel.
apm=allow_ints	Changes how the suspend service is handled (and may be necessary for some laptops).
apm=off	Disables APM (Advanced Power Management). This is useful because some BIOSes have buggy power management (APM) and tend to crash.
apm=power_off	Makes Red Hat Linux shut down the system by default. This is useful for SMP systems that do not shut down by default.
apm=realmode_power_off	Some BIOSes crash when trying to shut down the machine. This command changes the method of how this is done from the Windows NT method to the Windows 95 method.
dd	Prompts you to use a driver disk during the installation of Red Hat Linux.
display=IP:0	Allows remote display forwarding. In this command, IP should be replaced with the IP address of the system you want the display to appear on. On the system you want the display to appear on, you must execute the command xhost +remotehostname, where remotehostname is the name of the host you are running the original display from. Using the command xhost +remotehostname limits access to the remote display terminal and does not allow access from anyone or any system not specifically authorized for remote access.
driverdisk	Performs the same function as the dd command and also prompts you to use a driver disk during the installation of Red Hat Linux.
expert	Allows partitioning of removable media and prompts for driver disk.
ide=nodma	Disables DMA on all IDE devices and may be useful when having IDE-related problems.
isa	Prompts you for ISA device configuration.
lowres	Forces the graphical (GUI) installation program to run at a lower resolution (640x480).
mediacheck	Gives you the option of testing the integrity of the installation source (if an ISO-based method). Verifying that the ISO images are intact before you attempt an installation will help to avoid problems that are often encountered during an installation.
mem=xxxM	Allows you to override the amount of memory the kernel detects for the machine. This may be necessary for some older systems where only 16MB is detected and for some new machines where the video card shares the video memory with the main memory. When executing this command, xxx should be replaced with the amount of memory in megabytes.
nmi_watchdog=1	Enables the built-in kernel deadlock detector. This command can be used to debug hard kernel lockups. By executing periodic NMI (Non Maskable Interrupt) interrupts, the kernel can monitor whether any CPU has locked up and print out debugging messages as needed.
noapic	Tells the kernel not to use the APIC chip. This command may be helpful for some motherboards with a bad APIC (such as the Abit BP6) or with a buggy BIOS.
noht	Disables hyperthreading (when available in SMP systems).
nomce	Disables self-diagnosis checks performed on the CPU. The kernel enables self-diagnosis on the CPU by default (called Machine Check Exception). On some older Compaq machines, this check is run too often and may need to be disabled.
nomount	This command disables automatic mounting of any installed Linux partitions in rescue mode.
nopass	Disables the passing of keyboard and mouse information to stage 2 of the installation program. This is good for testing keyboard and mouse configuration screens during stage 2 of the installation program when performing a network installation.
nopcmcia	Ignores any PCMCIA controllers in system.
noprobe	Disables hardware detection and instead prompts the user for hardware information.
noshell	Disables shell access on virtual console 2 during an installation.
nousb	Disables the loading of USB support during the installation. If the installation program tends to hang early in the process, this command may be helpful.
nousbstorage	Disables the loading of the usbstorage module in the installation program's loader. It may help with device ordering on SCSI systems.
reboot=b	Changes the way the kernel tries to reboot the machine. If a kernel hang is experienced while the system is shutting down, this command will allow the system to reboot.
rescue	Runs rescue mode. Refer to Appendix A for more information about rescue mode.
resolution=	Tells the installation program which video mode to run. It accepts any standard resolution, such as 640x480, 800x600, 1024x768, and so on.
serial	Turns on serial console support.
skipddc	Skips the ddc monitor probe, which causes problems on some systems.
text	Disables the graphical installation program and forces the installation program to run in text mode.
updates	Prompts you to insert a floppy diskette containing updates (bug fixes). This is not needed if you are performing a network installation and have already placed the updated image contents in RHupdates/ on the server.

Kernel Options

Options can also be passed to the kernel. For example, to instruct the kernel to use all the RAM in a system with 128MB of RAM, enter:

boot: linux mem=128M

For text mode installations, use:

boot: linux text mem=128M

After entering any options, press Enter to boot using those options.

If you need to specify boot options to identify your hardware, please write them down. The boot options will be needed during the boot loader configuration portion of the installation (see the “Boot Loader Configuration” section later in this chapter for more information).

Booting Without Diskettes

The Red Hat Linux CD-ROM can be booted by computers that support bootable CD-ROMs. Not all computers support this feature, so if your system cannot boot from the CD-ROM, there is one other way to start the installation without using a boot diskette. The following method is specific to x86-based computers only.

If you have MS-DOS installed on your system, you can boot directly from the CD-ROM drive without using a boot diskette. To do this (assuming your CD-ROM is drive d:), use the following commands:

C:\> d: D:\> cd \dosutils D:\dosutils> autoboot.bat

This method will not work if run in an MS-DOS Command Prompt window — the autoboot.bat file must be executed with MS-DOS as the only operating system; that is, Windows cannot be running.

If your computer cannot boot directly from CD-ROM (and you cannot use a MS-DOS-based autoboot.bat), you will have to use a boot diskette to start the installation.