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.