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common/board_r.c
void board_init_r(gd_t *new_gd, ulong dest_addr)
{
#ifdef CONFIG_NEEDS_MANUAL_RELOC
int i;
#endif
#ifdef CONFIG_AVR32
mmu_init_r(dest_addr);
#endif
#if !defined(CONFIG_X86) && !defined(CONFIG_ARM) && !defined(CONFIG_ARM64)
gd = new_gd;
#endif
#ifdef CONFIG_NEEDS_MANUAL_RELOC
for (i = 0; i < ARRAY_SIZE(init_sequence_r); i++)
init_sequence_r[i] += gd->reloc_off;
#endif
if (initcall_run_list(<span style="color:#FF0000;">init_sequence_r</span>))
hang();
/* NOTREACHED - run_main_loop() does not return */
hang();
}
这里看看数组init_sequence_r的内容。
init_fnc_t init_sequence_r[] = {
initr_trace,
initr_reloc,
/* TODO: could x86/PPC have this also perhaps? */
#ifdef CONFIG_ARM
initr_caches,
#endif
initr_reloc_global_data,
#if defined(CONFIG_SYS_INIT_RAM_LOCK) && defined(CONFIG_E500)
initr_unlock_ram_in_cache,
#endif
initr_barrier,
initr_malloc,
#ifdef CONFIG_SYS_NONCACHED_MEMORY
initr_noncached,
#endif
bootstage_relocate,
#ifdef CONFIG_DM
initr_dm,
#endif
#ifdef CONFIG_ARM
board_init, /* Setup chipselects */
#endif
/*
* 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
stdio_init_tables,
initr_serial,
initr_announce,
INIT_FUNC_WATCHDOG_RESET
#ifdef CONFIG_NEEDS_MANUAL_RELOC
initr_manual_reloc_cmdtable,
#endif
#if defined(CONFIG_PPC) || defined(CONFIG_M68K)
initr_trap,
#endif
#ifdef CONFIG_ADDR_MAP
initr_addr_map,
#endif
#if defined(CONFIG_BOARD_EARLY_INIT_R)
board_early_init_r,
#endif
INIT_FUNC_WATCHDOG_RESET
#ifdef CONFIG_LOGBUFFER
initr_logbuffer,
#endif
#ifdef CONFIG_POST
initr_post_backlog,
#endif
INIT_FUNC_WATCHDOG_RESET
#ifdef CONFIG_SYS_DELAYED_ICACHE
initr_icache_enable,
#endif
#if defined(CONFIG_PCI) && defined(CONFIG_SYS_EARLY_PCI_INIT)
/*
* Do early PCI configuration _before_ the flash gets initialised,
* because PCU ressources are crucial for flash access on some boards.
*/
initr_pci,
#endif
#ifdef CONFIG_WINBOND_83C553
initr_w83c553f,
#endif
#ifdef CONFIG_ARCH_EARLY_INIT_R
arch_early_init_r,
#endif
power_init_board,
#ifndef CONFIG_SYS_NO_FLASH
initr_flash,
#endif
INIT_FUNC_WATCHDOG_RESET
#if defined(CONFIG_PPC) || defined(CONFIG_M68K)
/* initialize higher level parts of CPU like time base and timers */
cpu_init_r,
#endif
#ifdef CONFIG_PPC
initr_spi,
#endif
#if defined(CONFIG_X86) && defined(CONFIG_SPI)
init_func_spi,
#endif
#ifdef CONFIG_CMD_NAND
initr_nand,
#endif
#ifdef CONFIG_CMD_ONENAND
initr_onenand,
#endif
#ifdef CONFIG_GENERIC_MMC
initr_mmc,
#endif
#ifdef CONFIG_HAS_DATAFLASH
initr_dataflash,
#endif
initr_env,
#ifdef CONFIG_SYS_BOOTPARAMS_LEN
initr_malloc_bootparams,
#endif
INIT_FUNC_WATCHDOG_RESET
initr_secondary_cpu,
#ifdef CONFIG_SC3
initr_sc3_read_eeprom,
#endif
#if defined(CONFIG_ID_EEPROM) || defined(CONFIG_SYS_I2C_MAC_OFFSET)
mac_read_from_eeprom,
#endif
INIT_FUNC_WATCHDOG_RESET
#if defined(CONFIG_PCI) && !defined(CONFIG_SYS_EARLY_PCI_INIT)
/*
* Do pci configuration
*/
initr_pci,
#endif
<span style="color:#FF0000;">stdio_add_devices,</span>
initr_jumptable,
#ifdef CONFIG_API
initr_api,
#endif
console_init_r, /* fully init console as a device */
#ifdef CONFIG_DISPLAY_BOARDINFO_LATE
show_board_info,
#endif
#ifdef CONFIG_ARCH_MISC_INIT
arch_misc_init, /* miscellaneous arch-dependent init */
#endif
#ifdef CONFIG_MISC_INIT_R
misc_init_r, /* miscellaneous platform-dependent init */
#endif
INIT_FUNC_WATCHDOG_RESET
#ifdef CONFIG_CMD_KGDB
initr_kgdb,
#endif
interrupt_init,
#if defined(CONFIG_ARM) || defined(CONFIG_AVR32)
initr_enable_interrupts,
#endif
#if defined(CONFIG_X86) || defined(CONFIG_MICROBLAZE) || defined(CONFIG_AVR32) \
|| defined(CONFIG_M68K)
timer_init, /* initialize timer */
#endif
#if defined(CONFIG_STATUS_LED) && defined(STATUS_LED_BOOT)
initr_status_led,
#endif
/* PPC has a udelay(20) here dating from 2002. Why? */
#ifdef CONFIG_CMD_NET
initr_ethaddr,
#endif
#ifdef CONFIG_BOARD_LATE_INIT
board_late_init,
#endif
#ifdef CONFIG_FSL_FASTBOOT
initr_fastboot_setup,
#endif
#ifdef CONFIG_CMD_SCSI
INIT_FUNC_WATCHDOG_RESET
initr_scsi,
#endif
#ifdef CONFIG_CMD_DOC
INIT_FUNC_WATCHDOG_RESET
initr_doc,
#endif
#ifdef CONFIG_BITBANGMII
initr_bbmii,
#endif
#ifdef CONFIG_CMD_NET
INIT_FUNC_WATCHDOG_RESET
initr_net,
#endif
#ifdef CONFIG_POST
initr_post,
#endif
#if defined(CONFIG_CMD_PCMCIA) && !defined(CONFIG_CMD_IDE)
initr_pcmcia,
#endif
#if defined(CONFIG_CMD_IDE)
initr_ide,
#endif
#ifdef CONFIG_LAST_STAGE_INIT
INIT_FUNC_WATCHDOG_RESET
/*
* Some parts can be only initialized if all others (like
* Interrupts) are up and running (i.e. the PC-style ISA
* keyboard).
*/
last_stage_init,
#endif
#ifdef CONFIG_CMD_BEDBUG
INIT_FUNC_WATCHDOG_RESET
initr_bedbug,
#endif
#if defined(CONFIG_PRAM) || defined(CONFIG_LOGBUFFER)
initr_mem,
#endif
#ifdef CONFIG_PS2KBD
initr_kbd,
#endif
#ifdef CONFIG_FSL_FASTBOOT
initr_check_fastboot,
#endif
run_main_loop,
};
这里重点研究一下stdio_add_devices函数，该函数在common/stdio.c中实现
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;
最终调用video_init初始化屏幕并显示logo
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)只需在前面添加#define DEBUG即可打开该函数。
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。