Kernel Parameters at Boot Time

You can pass parameters to the kernel at boot time either permanently by editing the GRUB configuration file or temporarily by typing at the boot prompt. These control the behavior of the kernel when it boots in various ways. Current versions of SUSE use the showopts keyword in the GRUB configuration file, which has the unfortunate effect of hiding the parameters that are being passed. Actually what this keyword does is to hide the options that are listed before it and show those that appear after it.

If you remove showopts from the default entry line in /boot/grub/menu.lst, then at the next boot you will see exactly which boot parameters are being passed to the kernel when it loads. You will also be able to edit these parameters in the initial boot screen.

A list of supported parameters and their meanings are in the file:

/usr/src/linux/Documentation/kernel-parameters.txt

The following are a few examples of parameters that you might want to pass at boot time:

■ root=/dev/hda3: Sets the root device

■ vga = 791: Sets the framebuffer resolution to 1024 x 768

— ■ See Chapter 8 for more information on framebuffer graphics and resolution.

■ acpi=off: Disables Advanced Configuration and Power Interface (ACPI), often required on troublesome hardware

■ ide=nodma: Disables Direct Memory Access (DMA) access to IDE disks

■ noapic: Does not use the APIC interrupt controller j;These last three will be seen as part of the failsafe entry in /boot/grub/menu.lst ¡\- . „■ ..-r . because each of them can solve common problems with particular hardware.

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