RME Audio DIGI32/8 Specifications download pdf (Page 7)

1. Introduction

The kernel has the capability to accept information at boot in the form of a `command line', similar to an

argument list you would give to a program. In general this is used to supply the kernel with information about

hardware parameters that the kernel would not be able to determine on its own, or to avoid/override the values

that the kernel would otherwise detect.

It is the job of the boot loader (e.g. LILO, loadlin or Grub) to take this information from the user and put it in

a previously agreed upon place where the kernel can find it once it starts.

This present revision covers kernels up to and including v2.4.20. and v2.5.63

The BootPrompt−Howto is by:

Paul Gortmaker, p_gortmaker @ yahoo.com

information at the end of this document ( copyright) for information about redistribution of this document and

the usual `we are not responsible for what you manage to break...' type legal stuff.

1.1 Intended Audience and Applicability

Most Linux users should never have to even look at this document. Linux does an exceptionally good job at

detecting most hardware and picking reasonable default settings for most parameters. The information in this

document is aimed at users who might want to change some of the default settings to optimize the kernel to

their particular machine, or to a user who has `rolled their own' kernel to support a not so common piece of

hardware for which the automatic defaults are not optimal.

For the sake of this document it is best to break the boot arguments into two general categories; (a)ones

handled by the kernel and (b)those being handled by a device driver. Examples would be init= which tells

the kernel what the first program to run should be, versus aha154x= which tells a device driver for a SCSI

card what hardware resources it should use are. This document concentrates on giving detailed information on

those in (a) for reasons outlined below.

IMPORTANT NOTE: Driver related boot prompt arguments only apply to hardware drivers that are compiled

directly into the kernel. They have no effect on drivers that are loaded as modules. Most Linux distributions

come with a basic `bare−bones' kernel, and the drivers are small modules that are loaded after the kernel has

initialized. If you are unsure if you are using modules then try lsmod, look at man depmod and man

modprobe along with the contents of your /etc/modules.conf.

In light of this, device driver boot prompt arguments are only really used by a few people who are building

their own kernels, and thus have the kernel source at hand. These people are usually going to check the source

for the options and syntax required by that driver to get the most up to date info.

For example, if you were looking for what arguments could be passed to the AHA1542 SCSI driver, then you

would go to the linux/drivers/scsi directory, and look in the file aha1542.c for __setup(...

, ...). The first thing in brackets is the argument you provide at boot, and the second thing is the name of

the function that processes your argument. Usually near the top of this function or at the top of the source file

you will find a description of the boot time arguments that the driver accepts.

The Linux BootPrompt−HowTo

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