130 lines
3.5 KiB
Plaintext
130 lines
3.5 KiB
Plaintext
Kernel initialisation parameters on ARM Linux
|
|
---------------------------------------------
|
|
|
|
The following document describes the kernel initialisation parameter
|
|
structure, otherwise known as 'struct param_struct' which is used
|
|
for most ARM Linux architectures.
|
|
|
|
This structure is used to pass initialisation parameters from the
|
|
kernel loader to the Linux kernel proper, and may be short lived
|
|
through the kernel initialisation process. As a general rule, it
|
|
should not be referenced outside of arch/arm/kernel/setup.c:setup_arch().
|
|
|
|
There are a lot of parameters listed in there, and they are described
|
|
below:
|
|
|
|
page_size
|
|
|
|
This parameter must be set to the page size of the machine, and
|
|
will be checked by the kernel.
|
|
|
|
nr_pages
|
|
|
|
This is the total number of pages of memory in the system. If
|
|
the memory is banked, then this should contain the total number
|
|
of pages in the system.
|
|
|
|
If the system contains separate VRAM, this value should not
|
|
include this information.
|
|
|
|
ramdisk_size
|
|
|
|
This is now obsolete, and should not be used.
|
|
|
|
flags
|
|
|
|
Various kernel flags, including:
|
|
bit 0 - 1 = mount root read only
|
|
bit 1 - unused
|
|
bit 2 - 0 = load ramdisk
|
|
bit 3 - 0 = prompt for ramdisk
|
|
|
|
rootdev
|
|
|
|
major/minor number pair of device to mount as the root filesystem.
|
|
|
|
video_num_cols
|
|
video_num_rows
|
|
|
|
These two together describe the character size of the dummy console,
|
|
or VGA console character size. They should not be used for any other
|
|
purpose.
|
|
|
|
It's generally a good idea to set these to be either standard VGA, or
|
|
the equivalent character size of your fbcon display. This then allows
|
|
all the bootup messages to be displayed correctly.
|
|
|
|
video_x
|
|
video_y
|
|
|
|
This describes the character position of cursor on VGA console, and
|
|
is otherwise unused. (should not be used for other console types, and
|
|
should not be used for other purposes).
|
|
|
|
memc_control_reg
|
|
|
|
MEMC chip control register for Acorn Archimedes and Acorn A5000
|
|
based machines. May be used differently by different architectures.
|
|
|
|
sounddefault
|
|
|
|
Default sound setting on Acorn machines. May be used differently by
|
|
different architectures.
|
|
|
|
adfsdrives
|
|
|
|
Number of ADFS/MFM disks. May be used differently by different
|
|
architectures.
|
|
|
|
bytes_per_char_h
|
|
bytes_per_char_v
|
|
|
|
These are now obsolete, and should not be used.
|
|
|
|
pages_in_bank[4]
|
|
|
|
Number of pages in each bank of the systems memory (used for RiscPC).
|
|
This is intended to be used on systems where the physical memory
|
|
is non-contiguous from the processors point of view.
|
|
|
|
pages_in_vram
|
|
|
|
Number of pages in VRAM (used on Acorn RiscPC). This value may also
|
|
be used by loaders if the size of the video RAM can't be obtained
|
|
from the hardware.
|
|
|
|
initrd_start
|
|
initrd_size
|
|
|
|
This describes the kernel virtual start address and size of the
|
|
initial ramdisk.
|
|
|
|
rd_start
|
|
|
|
Start address in sectors of the ramdisk image on a floppy disk.
|
|
|
|
system_rev
|
|
|
|
system revision number.
|
|
|
|
system_serial_low
|
|
system_serial_high
|
|
|
|
system 64-bit serial number
|
|
|
|
mem_fclk_21285
|
|
|
|
The speed of the external oscillator to the 21285 (footbridge),
|
|
which control's the speed of the memory bus, timer & serial port.
|
|
Depending upon the speed of the cpu its value can be between
|
|
0-66 MHz. If no params are passed or a value of zero is passed,
|
|
then a value of 50 Mhz is the default on 21285 architectures.
|
|
|
|
paths[8][128]
|
|
|
|
These are now obsolete, and should not be used.
|
|
|
|
commandline
|
|
|
|
Kernel command line parameters. Details can be found elsewhere.
|