reactos/boot/armllb/boot.s

78 lines
2.4 KiB
ArmAsm

/*
* PROJECT: ReactOS Boot Loader
* LICENSE: BSD - See COPYING.ARM in the top level directory
* FILE: boot/armllb/boot.s
* PURPOSE: Implements the entry point for ARM machines
* PROGRAMMERS: ReactOS Portable Systems Group
*/
.title "ARM LLB Entry Point"
.include "ntoskrnl/include/internal/arm/kxarm.h"
.include "ntoskrnl/include/internal/arm/ksarm.h"
NESTED_ENTRY _start
PROLOG_END _start
#ifdef _BEAGLE_ // This is only used for TI BootROM on Beagle/Emulator for now
/*
* On Beagle, the boot is directly from TI BootROM that reads NAND flash.
* First word is size of program to load.
* Second word is load address of program. Since DDR is not initialized,
* we load to SDRAM at 40200000h. Max 64K.
*/
.word 0x8000
.word 0x40200000
#elif _ZOOM2_
/*
* On ZOOM2, we currently load from u-boot to make bring-up easier.
*
* In order to get ATAG and all that goodness, we have to fool u-boot into
* thinking we are a Linux ARM kernel.
*
* So this is a 'fake' uImage-format header, which will make u-boot grok our
* image and correctly execute it.
*
* Note that a data checksum is in the header, but thankfully we can disable
* the check.
*
* There's also a header checksum, but as long as there's no need to modify
* this header, we can leave it static.
*
* Finally, note that the "Image String" is sized as a 32-byte array in the
* uImage header format. The string chosen below is not only accurate, but
* also happens to fit exactly in 32 bytes, meaning we don't need to pad.
*/
.word 0x56190527 // Header Magic
.word 0x5E4B8444 // Checksum
.word 0x483BE54C // Timestamp
.word 0x0CA10000 // Image size (64K)
.word 0x00000081 // Load address
.word 0x40000081 // Entrypoint
.word 0x90873DD8 // Data Checksum ('setenv verify n' must be set!)
.byte 5 // Linux OS
.byte 2 // ARM
.byte 2 // Kernel
.byte 0 // No compression
.ascii "ReactOS ARM Low-Level Bootloader"
#endif
/* Load C entrypoint and setup LLB stack */
ldr lr, L_LlbStartup
ldr sp, L_BootStackEnd
bx lr
ENTRY_END _start
L_BootStackEnd:
#ifdef _BEAGLE_ // This is only used for TI BootROM on Beagle/Emulator for now
.long 0x00010000
#elif _ZOOM2_ // On ZOOM2 RAM starts at 0x80000000, not 0
.long 0x81014000
#else
#error Stack Address Not Defined
#endif
L_LlbStartup:
.long LlbStartup
/* EOF */