uboot调试总结(freescale平台为例)

uboot入口

arch/arm/lib/crt0.S

#include <config.h>
#include <asm-offsets.h>
#include <linux/linkage.h>

/*
 * This file handles the target-independent stages of the U-Boot
 * start-up where a C runtime environment is needed. Its entry point
 * is _main and is branched into from the target's start.S file.
 *
 * _main execution sequence is:
 *
 * 1. Set up initial environment for calling board_init_f().
 *    This environment only provides a stack and a place to store
 *    the GD ('global data') structure, both located in some readily
 *    available RAM (SRAM, locked cache...). In this context, VARIABLE
 *    global data, initialized or not (BSS), are UNAVAILABLE; only
 *    CONSTANT initialized data are available.
 *
 * 2. Call board_init_f(). This function prepares the hardware for
 *    execution from system RAM (DRAM, DDR...) As system RAM may not
 *    be available yet, , board_init_f() must use the current GD to
 *    store any data which must be passed on to later stages. These
 *    data include the relocation destination, the future stack, and
 *    the future GD location.
 *
 * (the following applies only to non-SPL builds)
 *
 * 3. Set up intermediate environment where the stack and GD are the
 *    ones allocated by board_init_f() in system RAM, but BSS and
 *    initialized non-const data are still not available.
 *
 * 4. Call relocate_code(). This function relocates U-Boot from its
 *    current location into the relocation destination computed by
 *    board_init_f().
 *
 * 5. Set up final environment for calling board_init_r(). This
 *    environment has BSS (initialized to 0), initialized non-const
 *    data (initialized to their intended value), and stack in system
 *    RAM. GD has retained values set by board_init_f(). Some CPUs
 *    have some work left to do at this point regarding memory, so
 *    call c_runtime_cpu_setup.
 *
 * 6. Branch to board_init_r().
 */

/*
 * entry point of crt0 sequence
 */

ENTRY(_main)

/*
 * Set up initial C runtime environment and call board_init_f(0).
 */

#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
	ldr	sp, =(CONFIG_SPL_STACK)
#else
	ldr	sp, =(CONFIG_SYS_INIT_SP_ADDR)
#endif
	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
	mov	r2, sp
	sub	sp, sp, #GD_SIZE	/* allocate one GD above SP */
	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
	mov	r9, sp		/* GD is above SP */
	mov	r1, sp
	mov	r0, #0
clr_gd:
	cmp	r1, r2			/* while not at end of GD */
	strlo	r0, [r1]		/* clear 32-bit GD word */
	addlo	r1, r1, #4		/* move to next */
	blo	clr_gd
#if defined(CONFIG_SYS_MALLOC_F_LEN)
	sub	sp, sp, #CONFIG_SYS_MALLOC_F_LEN
	str	sp, [r9, #GD_MALLOC_BASE]
#endif
	/* mov r0, #0 not needed due to above code */
	bl	board_init_f

#if ! defined(CONFIG_SPL_BUILD)

/*
 * Set up intermediate environment (new sp and gd) and call
 * relocate_code(addr_moni). Trick here is that we'll return
 * 'here' but relocated.
 */

	ldr	sp, [r9, #GD_START_ADDR_SP]	/* sp = gd->start_addr_sp */
	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
	ldr	r9, [r9, #GD_BD]		/* r9 = gd->bd */
	sub	r9, r9, #GD_SIZE		/* new GD is below bd */

	adr	lr, here
	ldr	r0, [r9, #GD_RELOC_OFF]		/* r0 = gd->reloc_off */
	add	lr, lr, r0
	ldr	r0, [r9, #GD_RELOCADDR]		/* r0 = gd->relocaddr */
	b	relocate_code
here:
/*
 * now relocate vectors
 */

	bl	relocate_vectors

/* Set up final (full) environment */

	bl	c_runtime_cpu_setup	/* we still call old routine here */
#endif
#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_FRAMEWORK)
# ifdef CONFIG_SPL_BUILD
	/* Use a DRAM stack for the rest of SPL, if requested */
	bl	spl_relocate_stack_gd
	cmp	r0, #0
	movne	sp, r0
# endif
	ldr	r0, =__bss_start	/* this is auto-relocated! */

#ifdef CONFIG_USE_ARCH_MEMSET
	ldr	r3, =__bss_end		/* this is auto-relocated! */
	mov	r1, #0x00000000		/* prepare zero to clear BSS */

	subs	r2, r3, r0		/* r2 = memset len */
	bl	memset
#else
	ldr	r1, =__bss_end		/* this is auto-relocated! */
	mov	r2, #0x00000000		/* prepare zero to clear BSS */

clbss_l:cmp	r0, r1			/* while not at end of BSS */
	strlo	r2, [r0]		/* clear 32-bit BSS word */
	addlo	r0, r0, #4		/* move to next */
	blo	clbss_l
#endif

#if ! defined(CONFIG_SPL_BUILD)
	bl coloured_LED_init
	bl red_led_on
#endif
	/* call board_init_r(gd_t *id, ulong dest_addr) */
	mov     r0, r9                  /* gd_t */
	ldr	r1, [r9, #GD_RELOCADDR]	/* dest_addr */
	/* call board_init_r */
	ldr	pc, =<span style="color:#FF0000;">board_init_r</span>	/* this is auto-relocated! */

	/* we should not return here. */
#endif

board/freescale/mx6sabresd下的mx6sabresd.c

void board_init_f(ulong dummy)
{
	/* setup AIPS and disable watchdog */
	arch_cpu_init();

	ccgr_init();
	gpr_init();

	/* iomux and setup of i2c */
	board_early_init_f();

	/* setup GP timer */
	timer_init();

	/* UART clocks enabled and gd valid - init serial console */
	preloader_console_init();

	/* DDR initialization */
	spl_dram_init();

	/* Clear the BSS. */
	memset(__bss_start, 0, __bss_end - __bss_start);

	/* load/boot image from boot device */
	<span style="color:#FF0000;">board_init_r(NULL, 0);</span>
}

函数board_init_r(NULL, 0)最终调用了arch/arm/lib/board.c

void board_init_r(gd_t *id, ulong dest_addr)
{
	ulong malloc_start;
#if !defined(CONFIG_SYS_NO_FLASH)
	ulong flash_size;
#endif

	gd->flags |= GD_FLG_RELOC;	/* tell others: relocation done */
	bootstage_mark_name(BOOTSTAGE_ID_START_UBOOT_R, "board_init_r");

	monitor_flash_len = (ulong)&__rel_dyn_end - (ulong)_start;

	/* Enable caches */
	enable_caches();

	debug("monitor flash len: %08lX\n", monitor_flash_len);
	board_init();	/* Setup chipselects */
	/*
	 * TODO: printing of the clock inforamtion of the board is now
	 * implemented as part of bdinfo command. Currently only support for
	 * davinci SOC's is added. Remove this check once all the board
	 * implement this.
	 */
#ifdef CONFIG_CLOCKS
	set_cpu_clk_info(); /* Setup clock information */
#endif
	serial_initialize();

	debug("Now running in RAM - U-Boot at: %08lx\n", dest_addr);

#ifdef CONFIG_LOGBUFFER
	logbuff_init_ptrs();
#endif
#ifdef CONFIG_POST
	post_output_backlog();
#endif

	/* The Malloc area is immediately below the monitor copy in DRAM */
	malloc_start = dest_addr - TOTAL_MALLOC_LEN;
	mem_malloc_init (malloc_start, TOTAL_MALLOC_LEN);

#ifdef CONFIG_ARCH_EARLY_INIT_R
	arch_early_init_r();
#endif
	power_init_board();

#if !defined(CONFIG_SYS_NO_FLASH)
	puts("Flash: ");

	flash_size = flash_init();
	if (flash_size > 0) {
# ifdef CONFIG_SYS_FLASH_CHECKSUM
		print_size(flash_size, "");
		/*
		 * Compute and print flash CRC if flashchecksum is set to 'y'
		 *
		 * NOTE: Maybe we should add some WATCHDOG_RESET()? XXX
		 */
		if (getenv_yesno("flashchecksum") == 1) {
			printf("  CRC: %08X", crc32(0,
				(const unsigned char *) CONFIG_SYS_FLASH_BASE,
				flash_size));
		}
		putc('\n');
# else	/* !CONFIG_SYS_FLASH_CHECKSUM */
		print_size(flash_size, "\n");
# endif /* CONFIG_SYS_FLASH_CHECKSUM */
	} else {
		puts(failed);
		hang();
	}
#endif

#if defined(CONFIG_CMD_NAND)
	puts("NAND:  ");
	nand_init();		/* go init the NAND */
#endif

#if defined(CONFIG_CMD_ONENAND)
	onenand_init();
#endif

#ifdef CONFIG_GENERIC_MMC
	puts("MMC:   ");
	mmc_initialize(gd->bd);
#endif

#ifdef CONFIG_CMD_SCSI
	puts("SCSI:  ");
	scsi_init();
#endif

#ifdef CONFIG_HAS_DATAFLASH
	AT91F_DataflashInit();
	dataflash_print_info();
#endif

	/* initialize environment */
	if (should_load_env())
		env_relocate();
	else
		set_default_env(NULL);

#if defined(CONFIG_CMD_PCI) || defined(CONFIG_PCI)
	arm_pci_init();
#endif

	<span style="color:#FF0000;">stdio_init();	/* get the devices list going. */</span>

	jumptable_init();

#if defined(CONFIG_API)
	/* Initialize API */
	api_init();
#endif

	console_init_r();	/* fully init console as a device */

#ifdef CONFIG_DISPLAY_BOARDINFO_LATE
# ifdef CONFIG_OF_CONTROL
	/* Put this here so it appears on the LCD, now it is ready */
	display_fdt_model(gd->fdt_blob);
# else
	checkboard();
# endif
#endif

#if defined(CONFIG_ARCH_MISC_INIT)
	/* miscellaneous arch dependent initialisations */
	arch_misc_init();
#endif
#if defined(CONFIG_MISC_INIT_R)
	/* miscellaneous platform dependent initialisations */
	misc_init_r();
#endif

	 /* set up exceptions */
	interrupt_init();
	/* enable exceptions */
	enable_interrupts();

	/* Initialize from environment */
	load_addr = getenv_ulong("loadaddr", 16, load_addr);

#ifdef CONFIG_BOARD_LATE_INIT
	board_late_init();
#endif

#ifdef CONFIG_FSL_FASTBOOT
	fastboot_setup();
#endif

#ifdef CONFIG_BITBANGMII
	bb_miiphy_init();
#endif
#if defined(CONFIG_CMD_NET)
	puts("Net:   ");
	eth_initialize(gd->bd);
#if defined(CONFIG_RESET_PHY_R)
	debug("Reset Ethernet PHY\n");
	reset_phy();
#endif
#endif

#ifdef CONFIG_POST
	post_run(NULL, POST_RAM | post_bootmode_get(0));
#endif

#if defined(CONFIG_PRAM) || defined(CONFIG_LOGBUFFER)
	/*
	 * Export available size of memory for Linux,
	 * taking into account the protected RAM at top of memory
	 */
	{
		ulong pram = 0;
		uchar memsz[32];

#ifdef CONFIG_PRAM
		pram = getenv_ulong("pram", 10, CONFIG_PRAM);
#endif
#ifdef CONFIG_LOGBUFFER
#ifndef CONFIG_ALT_LB_ADDR
		/* Also take the logbuffer into account (pram is in kB) */
		pram += (LOGBUFF_LEN + LOGBUFF_OVERHEAD) / 1024;
#endif
#endif
		sprintf((char *)memsz, "%ldk", (gd->ram_size / 1024) - pram);
		setenv("mem", (char *)memsz);
	}
#endif

#ifdef CONFIG_FSL_FASTBOOT
	check_fastboot();
#endif

	/* main_loop() can return to retry autoboot, if so just run it again. */
	for (;;) {
		main_loop();
	}

	/* NOTREACHED - no way out of command loop except booting */
}

int stdio_init(void)
{
	stdio_init_tables();
	<span style="color:#FF0000;">stdio_add_devices();</span>
	return 0;
}

int stdio_add_devices(void)
{
#ifdef CONFIG_SYS_I2C
	i2c_init_all();
#else
#if defined(CONFIG_HARD_I2C)
	i2c_init (CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
#endif
#endif
#ifdef CONFIG_LCD
	drv_lcd_init ();
#endif
#if defined(CONFIG_VIDEO) || defined(CONFIG_CFB_CONSOLE)
	<span style="color:#FF0000;">drv_video_init ();</span>
#endif
#ifdef CONFIG_KEYBOARD
	drv_keyboard_init ();
#endif
#ifdef CONFIG_LOGBUFFER
	drv_logbuff_init ();
#endif
	drv_system_init ();
	serial_stdio_init ();
#ifdef CONFIG_USB_TTY
	drv_usbtty_init ();
#endif
#ifdef CONFIG_NETCONSOLE
	drv_nc_init ();
#endif
#ifdef CONFIG_JTAG_CONSOLE
	drv_jtag_console_init ();
#endif
#ifdef CONFIG_CBMEM_CONSOLE
	cbmemc_init();
#endif

	return 0;
}

int drv_video_init(void)
{
	int skip_dev_init;
	struct stdio_dev console_dev;

	/* Check if video initialization should be skipped */
	<span style="color:#FF0000;">if (board_video_skip())</span>
		return 0;

	/* Init video chip - returns with framebuffer cleared */
	<span style="color:#FF0000;">skip_dev_init = (video_init() == -1);</span>

	if (board_cfb_skip())
		return 0;

#if !defined(CONFIG_VGA_AS_SINGLE_DEVICE)
	debug("KBD: Keyboard init ...\n");
	skip_dev_init |= (VIDEO_KBD_INIT_FCT == -1);
#endif

	if (skip_dev_init)
		return 0;

	/* Init vga device */
	memset(&console_dev, 0, sizeof(console_dev));
	strcpy(console_dev.name, "vga");
	console_dev.ext = DEV_EXT_VIDEO;	/* Video extensions */
	console_dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_SYSTEM;
	console_dev.putc = video_putc;	/* 'putc' function */
	console_dev.puts = video_puts;	/* 'puts' function */

#if !defined(CONFIG_VGA_AS_SINGLE_DEVICE)
	/* Also init console device */
	console_dev.flags |= DEV_FLAGS_INPUT;
	console_dev.tstc = VIDEO_TSTC_FCT;	/* 'tstc' function */
	console_dev.getc = VIDEO_GETC_FCT;	/* 'getc' function */
#endif /* CONFIG_VGA_AS_SINGLE_DEVICE */

	if (stdio_register(&console_dev) != 0)
		return 0;

	/* Return success */
	return 1;
}

board_video_skip获取要初始化的屏幕参数arch/arm/imx-common/video.c

int board_video_skip(void)
{
	int i;
	int ret;
	char const *panel = getenv("panel");

	if (!panel) {
		for (i = 0; i < display_count; i++) {
			struct display_info_t const *dev = displays+i;
			if (dev->detect && dev->detect(dev)) {
				panel = dev->mode.name;
				printf("auto-detected panel %s\n", panel);
				break;
			}
		}
		if (!panel) {
			panel = displays[0].mode.name;
			printf("No panel detected: default to %s\n", panel);
			i = 2;
		}
	} else {
		for (i = 0; i < display_count; i++) {
			if (!strcmp(panel, displays[i].mode.name))
				break;
		}
	}

	if (i < display_count) {
		ret = <span style="color:#FF0000;">ipuv3_fb_init</span>(&displays[i].mode, 0,
				    displays[i].pixfmt);
		if (!ret) {
			if (displays[i].enable)
				displays[i].enable(displays + i);

			printf("Display: %s (%ux%u)\n",
			       displays[i].mode.name,
			       displays[i].mode.xres,
			       displays[i].mode.yres);
		} else
			printf("LCD %s cannot be configured: %d\n",
			       displays[i].mode.name, ret);
	} else {
		printf("unsupported panel %s\n", panel);
		return -EINVAL;
	}

	return 0;

void video_inti(void)

{

------

video_hw_init  //屏幕初始化(根据上面获取到的参数)

video_logo();//刷logo(位于tools/logos/xxx.bmp,该bmp位图被编译成数组，最终被刷出来)

------

}

在刷logo的过程中会调用flush_cache刷新一下缓冲区，否则图像会变得离散。

if (cfb_do_flush_cache)
        flush_cache(VIDEO_FB_ADRS, VIDEO_SIZE)；

VIDEO_FB_ADRS显示基地址

VIDEO_SIZE显示的大小

在uboot中有很多debug函数，打开debug函数可以看到uboot中函数的调用过程。

dedug函数(include/common.h)的定义为

#ifdef DEBUG
#define _DEBUG	1
#else
#define _DEBUG	0
#endif

#ifndef pr_fmt
#define pr_fmt(fmt) fmt
#endif

/*
 * Output a debug text when condition "cond" is met. The "cond" should be
 * computed by a preprocessor in the best case, allowing for the best
 * optimization.
 */
#define debug_cond(cond, fmt, args...)				do {								if (cond)							printf(pr_fmt(fmt), ##args);		} while (0)

#define debug(fmt, args...)				debug_cond(_DEBUG, fmt, ##args)

另外,查找函数调用关系时，如果有多个地方被定义，不确定具体的定义位置时，只需到该目录下，ls -al *.o，即可确认真正被调用的函数。因为该函数被编译了，就会

生成.o文件。

uboot调试总结(freescale平台为例)

原文：http://blog.csdn.net/mike8825/article/details/51284681