/*
 * \brief   Startup code for the Genode Kernel on ARM
 * \author  Martin Stein
 * \author  Stefan Kalkowski
 * \date    2011-10-01
 */

/*
 * Copyright (C) 2011-2012 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU General Public License version 2.
 */

.section .text

	/* ELF entry symbol */
	.global _start
	_start:

		/* idle a little initially because 'u-boot' likes it this way */
		.rept 8
		nop
		.endr

		/* zero-fill BSS segment */
		.extern _bss_start
		.extern _bss_end
		ldr r0, =_bss_start
		ldr r1, =_bss_end
		mov r2, #0
		sub r1, r1, #4
		1:
		str r2, [r0]
		add r0, r0, #4
		cmp r0, r1
		bne 1b

		/* call kernel routine */
		.extern kernel
		_start_kernel:
		ldr sp, =_kernel_stack_high
		bl kernel

		/* jump to code that kernel has designated for when he has returned */
		ldr r1, =_call_after_kernel
		ldr r1, [r1]
		add pc, r1, #0

	/* handle for dynamic symbol objects */
	.align 3
	.global __dso_handle
	__dso_handle: .long 0

.section .bss

	/* instruction pointer wich gets loaded when kernel returns */
	.align 3
	.global _call_after_kernel
	_call_after_kernel:  .long 0

	/* kernel stack */
	.align 3
	.space 64*1024
	.global _kernel_stack_high
	_kernel_stack_high:

	/* main thread UTCB pointer for the Genode thread API */
	.align 3
	.global _main_utcb
	_main_utcb:  .long 0