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diff --git a/Documentation/arm/Setup b/Documentation/arm/Setup new file mode 100644 index 000000000000..0abd0720d7ed --- /dev/null +++ b/Documentation/arm/Setup @@ -0,0 +1,129 @@ +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 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. |