Setup 3.5 KB

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  1. Kernel initialisation parameters on ARM Linux
  2. ---------------------------------------------
  3. The following document describes the kernel initialisation parameter
  4. structure, otherwise known as 'struct param_struct' which is used
  5. for most ARM Linux architectures.
  6. This structure is used to pass initialisation parameters from the
  7. kernel loader to the Linux kernel proper, and may be short lived
  8. through the kernel initialisation process. As a general rule, it
  9. should not be referenced outside of arch/arm/kernel/setup.c:setup_arch().
  10. There are a lot of parameters listed in there, and they are described
  11. below:
  12. page_size
  13. This parameter must be set to the page size of the machine, and
  14. will be checked by the kernel.
  15. nr_pages
  16. This is the total number of pages of memory in the system. If
  17. the memory is banked, then this should contain the total number
  18. of pages in the system.
  19. If the system contains separate VRAM, this value should not
  20. include this information.
  21. ramdisk_size
  22. This is now obsolete, and should not be used.
  23. flags
  24. Various kernel flags, including:
  25. bit 0 - 1 = mount root read only
  26. bit 1 - unused
  27. bit 2 - 0 = load ramdisk
  28. bit 3 - 0 = prompt for ramdisk
  29. rootdev
  30. major/minor number pair of device to mount as the root filesystem.
  31. video_num_cols
  32. video_num_rows
  33. These two together describe the character size of the dummy console,
  34. or VGA console character size. They should not be used for any other
  35. purpose.
  36. It's generally a good idea to set these to be either standard VGA, or
  37. the equivalent character size of your fbcon display. This then allows
  38. all the bootup messages to be displayed correctly.
  39. video_x
  40. video_y
  41. This describes the character position of cursor on VGA console, and
  42. is otherwise unused. (should not be used for other console types, and
  43. should not be used for other purposes).
  44. memc_control_reg
  45. MEMC chip control register for Acorn Archimedes and Acorn A5000
  46. based machines. May be used differently by different architectures.
  47. sounddefault
  48. Default sound setting on Acorn machines. May be used differently by
  49. different architectures.
  50. adfsdrives
  51. Number of ADFS/MFM disks. May be used differently by different
  52. architectures.
  53. bytes_per_char_h
  54. bytes_per_char_v
  55. These are now obsolete, and should not be used.
  56. pages_in_bank[4]
  57. Number of pages in each bank of the systems memory (used for RiscPC).
  58. This is intended to be used on systems where the physical memory
  59. is non-contiguous from the processors point of view.
  60. pages_in_vram
  61. Number of pages in VRAM (used on Acorn RiscPC). This value may also
  62. be used by loaders if the size of the video RAM can't be obtained
  63. from the hardware.
  64. initrd_start
  65. initrd_size
  66. This describes the kernel virtual start address and size of the
  67. initial ramdisk.
  68. rd_start
  69. Start address in sectors of the ramdisk image on a floppy disk.
  70. system_rev
  71. system revision number.
  72. system_serial_low
  73. system_serial_high
  74. system 64-bit serial number
  75. mem_fclk_21285
  76. The speed of the external oscillator to the 21285 (footbridge),
  77. which control's the speed of the memory bus, timer & serial port.
  78. Depending upon the speed of the cpu its value can be between
  79. 0-66 MHz. If no params are passed or a value of zero is passed,
  80. then a value of 50 Mhz is the default on 21285 architectures.
  81. paths[8][128]
  82. These are now obsolete, and should not be used.
  83. commandline
  84. Kernel command line parameters. Details can be found elsewhere.