head.s

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

/* $Id: head.S,v 1.17 2000/03/06 12:44:24 gniibe Exp $
 *
 *  arch/sh/kernel/head.S
 *
 *  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Head.S contains the SH exception handlers and startup code.
 */
#include <linux/linkage.h>

	.section	.empty_zero_page, "aw"
ENTRY(empty_zero_page)
	.long	1		/* MOUNT_ROOT_RDONLY */
	.long	0		/* RAMDISK_FLAGS */
	.long	0x0200		/* ORIG_ROOT_DEV */
	.long	1		/* LOADER_TYPE */
	.long	0x00360000	/* INITRD_START */
	.long	0x000a0000	/* INITRD_SIZE */
	.long	0
	.balign 4096,0,4096

	.text	
/*
 * Condition at the entry of _stext:
 *
 *   BSC has already been initialized.
 *   INTC may or may not be initialized.
 *   VBR may or may not be initialized.
 *   MMU may or may not be initialized.
 *   Cache may or may not be initialized.
 *   Hardware (including on-chip modules) may or may not be initialized. 
 *
 */
ENTRY(_stext)
	!			Initialize Status Register
	mov.l	1f, $r0		! MD=1, RB=0, BL=0, IMASK=0xF
	ldc	$r0, $sr
	!			Initialize global interrupt mask
	mov	#0, $r0
	ldc	$r0, $r6_bank
	!
	mov.l	2f, $r0
	mov	$r0, $r15	! Set initial r15 (stack pointer)
	mov	#0x20, $r1	!
	shll8	$r1		! $r1 = 8192
	sub	$r1, $r0	!
	ldc	$r0, $r7_bank	! ... and init_task
	!
#if defined(__SH4__)
	!                       Initialize fpu
	mov.l   7f, $r0
	jsr     @$r0
	 nop
#endif
	!			Enable cache
	mov.l	6f, $r0
	jsr	@$r0
	 nop
	!			Clear BSS area
	mov.l	3f, $r1
	add	#4, $r1
	mov.l	4f, $r2
	mov	#0, $r0
9:	cmp/hs	$r2, $r1
	bf/s	9b		! while (r1 < r2)
	 mov.l	$r0,@-$r2
	!			Start kernel
	mov.l	5f, $r0
	jmp	@$r0
	 nop

	.balign 4
1:	.long	0x400000F0		! MD=1, RB=0, BL=0, FD=0, IMASK=0xF
2:	.long	SYMBOL_NAME(stack)
3:	.long	SYMBOL_NAME(__bss_start)
4:	.long	SYMBOL_NAME(_end)
5:	.long	SYMBOL_NAME(start_kernel)
6:	.long	SYMBOL_NAME(cache_init)
#if defined(__SH4__)
7:	.long   SYMBOL_NAME(fpu_init)
#endif