README.nokia_rx51 4.4 KB

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  1. Board: Nokia RX-51 aka N900
  2. This board definition results in a u-boot.bin which can be chainloaded
  3. from NOLO in qemu or on a real N900. It does very little hardware config
  4. because NOLO has already configured the board. Only needed is enabling
  5. internal eMMC memory via twl4030 regulator which is not enabled by NOLO.
  6. NOLO is expecting a kernel image and will treat any image it finds in
  7. onenand as such. This u-boot is intended to be flashed to the N900 like
  8. a kernel. In order to transparently boot the original kernel, it will be
  9. appended to u-boot.bin at 0x40000. NOLO will load the entire image into
  10. (random) memory and execute u-boot, which saves hw revision, boot reason
  11. and boot mode ATAGs set by NOLO. Then the bootscripts will attempt to load
  12. uImage or boot.scr from a fat, ext2/ext3 or ext4 filesystem in external
  13. SD card or internal eMMC memory. If this fails or keyboard is closed then
  14. the appended kernel image will be booted using some generated and some
  15. stored ATAGs (see boot order).
  16. For generating combined image of u-boot and kernel there is a simple script
  17. called u-boot-gen-combined. It is available in following repository:
  18. https://github.com/pali/u-boot-maemo
  19. There is support for hardware watchdog. Hardware watchdog is started by
  20. NOLO so u-boot must kick watchdog to prevent reboot device (but not very
  21. often, max every 2 seconds). There is also support for framebuffer display
  22. output with ANSI escape codes and the N900 HW keyboard input. USB tty works
  23. but is disabled because it prevents the current Maemo kernel from booting.
  24. When U-Boot is starting it enable IBE bit in Auxiliary Control Register,
  25. which is needed for Thumb-2 ISA support. It is workaround for errata 430973.
  26. Default boot order:
  27. * 0. if keyboard is closed boot automatically attached kernel image
  28. * 1. try boot from external SD card
  29. * 2. try boot from internal eMMC memory
  30. * 3. try boot from attached kernel image
  31. Boot from SD or eMMC in this order:
  32. * 1.
  33. * 1.1 find boot.scr on first fat partition
  34. * 1.2 find uImage on first fat partition
  35. * 1.3 same order for 2. - 4. fat partition
  36. * 2. same as 1. but for ext2/3 partition
  37. * 3. same as 1. but for ext4 partition
  38. Available additional commands/variables:
  39. * run sercon - Use serial port for control
  40. * run usbcon - Use usbtty for control
  41. * run vgacon - Use framebuffer and HW keyboard for control (default)
  42. * run sdboot - Boot from external SD card (see boot order)
  43. * run emmcboot - Boot from internal eMMC memory (see boot order)
  44. * run attachboot - Boot attached kernel image (attached to U-Boot binary)
  45. * run scriptload - Load boot script ${mmcscriptfile}
  46. * run scriptboot - Run loaded boot script
  47. * run kernload - Load kernel image ${mmckernfile}
  48. * run initrdload - Load initrd image ${mmcinitrdfile}
  49. * run kernboot - Boot loaded kernel image
  50. * run kerninitrdboot - Boot loaded kernel image with loaded initrd image
  51. * run trymmcscriptboot - Try to load and boot script ${mmcscriptfile}
  52. * run trymmckernboot - Try to load and boot kernel image ${mmckernfile}
  53. * run trymmckerninitrdboot - Try to load and boot kernel image ${mmckernfile}
  54. with initrd image ${mmcinitrdfile}
  55. Additional variables for loading files from mmc:
  56. * mmc ${mmcnum} (0 - external, 1 - internal)
  57. * partition number ${mmcpart} (1 - 4)
  58. * parition type ${mmctype} (fat, ext2, ext4)
  59. Additional variables for booting kernel:
  60. * setup_omap_atag - Add OMAP table into atags structure (needs maemo kernel)
  61. * setup_console_atag - Enable serial console in OMAP table
  62. * setup_boot_reason_atag - Change boot reason in OMAP table
  63. * setup_boot_mode_atag - Change boot mode in OMAP table
  64. Variable setup_omap_atag is automatically set when booting attached kernel.
  65. When variable setup_omap_atag is set, variable setup_console_atag is unset
  66. and u-boot standard output is set to serial then setup_console_atag is
  67. automatically set to 1. So output from Maemo kernel would go to serial port.
  68. USB TTY:
  69. Maemo kernel 2.6.28 will crash if u-boot enable usb tty. So USB TTY is disabled.
  70. For enabling USB TTY just add this line to file include/configs/nokia_rx51.h
  71. #define CONFIG_USB_TTY
  72. UBIFS support:
  73. UBIFS support is disabled, because U-Boot image is too big and cannot be
  74. flashed with attached zImage to RX-51 kernel nand area. For enabling UBIFS
  75. support add following lines into file configs/nokia_rx51_defconfig
  76. CONFIG_CMD_UBI=y
  77. CONFIG_CMD_UBIFS=y
  78. CONFIG_MTD_UBI_FASTMAP=y
  79. CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT=1