reactos/boot/armllb/boot.s

   1 /*
   2  * PROJECT:         ReactOS Boot Loader
   3  * LICENSE:         BSD - See COPYING.ARM in the top level directory
   4  * FILE:            boot/armllb/boot.s
   5  * PURPOSE:         Implements the entry point for ARM machines
   6  * PROGRAMMERS:     ReactOS Portable Systems Group
   7  */
   8
   9     .title "ARM LLB Entry Point"
  10     .include "ntoskrnl/include/internal/arm/kxarm.h"
  11     .include "ntoskrnl/include/internal/arm/ksarm.h"
  12
  13     NESTED_ENTRY _start
  14     PROLOG_END _start
  15
  16 #ifdef _BEAGLE_ // This is only used for TI BootROM on Beagle/Emulator for now
  17     /*
  18      * On Beagle, the boot is directly from TI BootROM that reads NAND flash.
  19      * First word is size of program to load.
  20      * Second word is load address of program. Since DDR is not initialized,
  21      * we load to SDRAM at 40200000h. Max 64K.
  22      */
  23     .word 0x8000
  24     .word 0x40200000
  25 #elif _ZOOM2_
  26         /*
  27          * On ZOOM2, we currently load from u-boot to make bring-up easier.
  28          *
  29          * In order to get ATAG and all that goodness, we have to fool u-boot into
  30          * thinking we are a Linux ARM kernel.
  31          *
  32          * So this is a 'fake' uImage-format header, which will make u-boot grok our
  33          * image and correctly execute it.
  34          *
  35          * Note that a data checksum is in the header, but thankfully we can disable
  36          * the check.
  37          *
  38          * There's also a header checksum, but as long as there's no need to modify
  39          * this header, we can leave it static.
  40          *
  41          * Finally, note that the "Image String" is sized as a 32-byte array in the
  42          * uImage header format. The string chosen below is not only accurate, but
  43          * also happens to fit exactly in 32 bytes, meaning we don't need to pad.
  44          */
  45         .word 0x56190527 // Header Magic
  46         .word 0x5E4B8444 // Checksum
  47         .word 0x483BE54C // Timestamp
  48         .word 0x0CA10000 // Image size (64K)
  49         .word 0x00000081 // Load address
  50         .word 0x40000081 // Entrypoint
  51         .word 0x90873DD8 // Data Checksum ('setenv verify n' must be set!)
  52         .byte 5                  // Linux OS
  53         .byte 2                  // ARM
  54         .byte 2                  // Kernel
  55         .byte 0                  // No compression
  56         .ascii "ReactOS ARM Low-Level Bootloader"
  57 #endif
  58
  59     /* Load C entrypoint and setup LLB stack */
  60     ldr lr, L_LlbStartup
  61     ldr sp, L_BootStackEnd
  62     bx lr
  63     ENTRY_END _start
  64
  65 L_BootStackEnd:
  66 #ifdef _BEAGLE_ // This is only used for TI BootROM on Beagle/Emulator for now
  67     .long 0x00010000
  68 #elif _ZOOM2_ // On ZOOM2 RAM starts at 0x80000000, not 0
  69         .long 0x81014000
  70 #else
  71 #error Stack Address Not Defined
  72 #endif
  73
  74 L_LlbStartup:
  75     .long LlbStartup
  76
  77 /* EOF */