U-BOOT移植过程详解: u-boot.bin

申明

  本着学习交流的原则, 将个人移植u-boot的过程做一个记录. 文章参考了csdn blog里面的很多内容, 有的已经记不得出处了, 只好把当时的摘要直接贴出来. 如果冒犯, 还请见谅. 如有侵权, 请与我邮件联系. 谢谢!

u-boot.bin

这里的u-boot.bin指的是不包含SPL的stage2部分的代码. 它会被SPL搬移到RAM的某个地址处开始运行. 本篇下面提到的u-boot.bin时, 也是指的这个概念.

u-boot.bin的文件组成

当我们在uboot下执行make命令的时候, 它最核心的功能是执行Makefile中的all目标编译出相应的文件. 我们来看看这个all目标

all:		$(ALL-y) $(SUBDIR_EXAMPLES)

all依赖于 $(ALL-y) 和 $(SUBDIR_EXAMPLES), 这里我只关注ALL-y, 如下:

# Always append ALL so that arch config.mk's can add custom ones
ALL-y += $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map

ALL-$(CONFIG_NAND_U_BOOT) += $(obj)u-boot-nand.bin
ALL-$(CONFIG_ONENAND_U_BOOT) += $(obj)u-boot-onenand.bin
ALL-$(CONFIG_SPL) += $(obj)spl/u-boot-spl.bin
ALL-$(CONFIG_SPL_FRAMEWORK) += $(obj)u-boot.img
ALL-$(CONFIG_TPL) += $(obj)tpl/u-boot-tpl.bin
ALL-$(CONFIG_OF_SEPARATE) += $(obj)u-boot.dtb $(obj)u-boot-dtb.bin
ifneq ($(CONFIG_SPL_TARGET),)
ALL-$(CONFIG_SPL) += $(obj)$(subst ",,$(CONFIG_SPL_TARGET))
endif

# enable combined SPL/u-boot/dtb rules for tegra
ifneq ($(CONFIG_TEGRA),)
ifeq ($(CONFIG_OF_SEPARATE),y)
ALL-y += $(obj)u-boot-dtb-tegra.bin
else
ALL-y += $(obj)u-boot-nodtb-tegra.bin
endif
endif

注意红色部分的代码, 它表面all目标依赖 $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map

先忽略System.map, 在看下面一段

$(obj)u-boot.srec:	$(obj)u-boot
		$(OBJCOPY) -O srec $< $@

$(obj)u-boot.bin:	$(obj)u-boot
		$(OBJCOPY) ${OBJCFLAGS} -O binary $< $@
		$(BOARD_SIZE_CHECK)

它们都依赖于u-boot

那么在看看u-boot的依赖关系

ifeq ($(CONFIG_SANDBOX),y)
GEN_UBOOT = \
		cd $(LNDIR) && $(CC) $(SYMS) -T $(obj)u-boot.lds \
			-Wl,--start-group $(__LIBS) -Wl,--end-group \
			$(PLATFORM_LIBS) -Wl,-Map -Wl,u-boot.map -o u-boot
else
GEN_UBOOT = \
		cd $(LNDIR) && $(LD) $(LDFLAGS) $(LDFLAGS_$(@F)) \
			$(__OBJS) \
			--start-group $(__LIBS) --end-group $(PLATFORM_LIBS) \
			-Map u-boot.map -o u-boot
endif

$(obj)u-boot:	depend \
		$(SUBDIR_TOOLS) $(OBJS) $(LIBBOARD) $(LIBS) $(LDSCRIPT) $(obj)u-boot.lds
		$(GEN_UBOOT)

• depend: 参考附录中的depend
• $(SUBDIR_TOOLS) $(OBJS) $(LIBBOARD) $(LIBS) : 各个子目录
  
• $(LDSCRIPT) : 如下, 默认就是在arch/arm/cpu/下面的u-boot.lds
  

• # If board code explicitly specified LDSCRIPT or CONFIG_SYS_LDSCRIPT, use
  # that (or fail if absent).  Otherwise, search for a linker script in a
  # standard location.
  
  
  LDSCRIPT_MAKEFILE_DIR = $(dir $(LDSCRIPT))
  
  
  ifndef LDSCRIPT
  	#LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds.debug
  	ifdef CONFIG_SYS_LDSCRIPT
  		# need to strip off double quotes
  		LDSCRIPT := $(subst ",,$(CONFIG_SYS_LDSCRIPT))
  	endif
  endif
  
  
  # If there is no specified link script, we look in a number of places for it
  ifndef LDSCRIPT
  	ifeq ($(CONFIG_NAND_U_BOOT),y)
  		LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot-nand.lds
  		ifeq ($(wildcard $(LDSCRIPT)),)
  			LDSCRIPT := $(TOPDIR)/$(CPUDIR)/u-boot-nand.lds
  		endif
  	endif
  	ifeq ($(wildcard $(LDSCRIPT)),)
  		LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds
  	endif
  	ifeq ($(wildcard $(LDSCRIPT)),)
  		LDSCRIPT := $(TOPDIR)/$(CPUDIR)/u-boot.lds
  	endif
  	ifeq ($(wildcard $(LDSCRIPT)),)
  		LDSCRIPT := $(TOPDIR)/arch/$(ARCH)/cpu/u-boot.lds
  		# We don't expect a Makefile here
  		LDSCRIPT_MAKEFILE_DIR =
  	endif
  	ifeq ($(wildcard $(LDSCRIPT)),)
  $(error could not find linker script)
  	endif
  endif

• $(GEN_UBOOT) : 利用ld命令链接生成u-boot
  

OK, 这就是u-boot.bin相关的文件组成. 如果想知道到底编译了哪些目录, 可以根据Makefile仔细研究它到底依赖了哪些文件夹. 原理与上面类似.

代码分析

u-boot.lds: 它的位置在上文中我们分析了

• 根据u-boot.lds中的规则, 与SPL阶段一样, CPUDIR/start.o被放在了最前面. 它与SPL阶段对应的是同一个文件arch/arm/cpu/armv7/start.S

start.S

与 SPL中start.S的执行流程基本一致, 不同的地方是, 这里的start.S会负责处理异常中断.

ctr0.S

_main

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 */
	sub	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	r0, #0
	bl	board_init_f

• sp, gd相关, 参考SPL中的_main
• bl board_init_f: 跳转到board_init_f
  
  • SPL最后也是跳转到board_init_f, 它们有什么不一样吗? 是的, 完全不一样. 由于SPL阶段与u-boot.bin阶段编译选项的不同, 会导致不同的c文件被编译. 这里的board_init_f实现函数与SPL阶段board_init_f的实现函数不是同一个.

#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:

/* Set up final (full) environment */

	bl	c_runtime_cpu_setup	/* we still call old routine here */

	ldr	r0, =__bss_start	/* this is auto-relocated! */
	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

	bl coloured_LED_init
	bl red_led_on

	/* 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, =board_init_r	/* this is auto-relocated! */

	/* we should not return here. */

#endif

• #if ! defined(CONFIG_SPL_BUILD) : 说明只有在u-boot.bin阶段, 才会执行这段代码. 这里也与SPL阶段不一样
  
• b relocate_code : 把代码relocate到编译地址处
  
• ldr pc, =board_init_r: 调用board_init_r, 同样, 该函数实现的地方与SPL阶段的也不一样.
  

arch/arm/lib/board.c

board_init_f

memset((void *)gd, 0, sizeof(gd_t));

• gd的定义在board.c里面, 有一行: DECLARE_GLOBAL_DATA_PTR;
• memset清零, 说明从这里开始, 重新对gd进行初始化.
• 那我们在前面的代码很看到很多对gd的操作啊, 有什么用呢? 主要是在一些汇编代码里面引用了gd的相关变量. 哪些变量可能被引用到呢? 在这里 lib/asm-offsets.c

#ifdef CONFIG_OF_EMBED
	/* Get a pointer to the FDT */
	gd->fdt_blob = _binary_dt_dtb_start;
#elif defined CONFIG_OF_SEPARATE
	/* FDT is at end of image */
	gd->fdt_blob = (void *)(_end_ofs + _TEXT_BASE);
#endif
	/* Allow the early environment to override the fdt address */
	gd->fdt_blob = (void *)getenv_ulong("fdtcontroladdr", 16,
						(uintptr_t)gd->fdt_blob);

• fdt相关, 类似于linux内核里面的dtb. 暂不分析

	for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
		if ((*init_fnc_ptr)() != 0) {
			hang ();
		}
	}

• 依次调用init_sequence里面的函数, 如果某个函数执行失败, 即返回值不为0, 就会hang
• 具体有哪些函数, 见下文.

#ifdef CONFIG_OF_CONTROL
	/* For now, put this check after the console is ready */
	if (fdtdec_prepare_fdt()) {
		panic("** CONFIG_OF_CONTROL defined but no FDT - please see "
			"doc/README.fdt-control");
	}
#endif

• fdt相关, 暂不分析

#if defined(CONFIG_SYS_MEM_TOP_HIDE)
	/*
	 * Subtract specified amount of memory to hide so that it won't
	 * get "touched" at all by U-Boot. By fixing up gd->ram_size
	 * the Linux kernel should now get passed the now "corrected"
	 * memory size and won't touch it either. This should work
	 * for arch/ppc and arch/powerpc. Only Linux board ports in
	 * arch/powerpc with bootwrapper support, that recalculate the
	 * memory size from the SDRAM controller setup will have to
	 * get fixed.
	 */
	gd->ram_size -= CONFIG_SYS_MEM_TOP_HIDE;
#endif

• 隐藏一块MEM, uboot不会touch它. 同样也可以做到让linux kernel不touch它.
• 一般ppc或者powerpc体系架构才会用到这个

	addr = CONFIG_SYS_SDRAM_BASE + gd->ram_size;

#ifdef CONFIG_LOGBUFFER
#ifndef CONFIG_ALT_LB_ADDR
	/* reserve kernel log buffer */
	addr -= (LOGBUFF_RESERVE);
	debug("Reserving %dk for kernel logbuffer at %08lx\n", LOGBUFF_LEN,
		addr);
#endif
#endif

#ifdef CONFIG_PRAM
	/*
	 * reserve protected RAM
	 */
	reg = getenv_ulong("pram", 10, CONFIG_PRAM);
	addr -= (reg << 10);		/* size is in kB */
	debug("Reserving %ldk for protected RAM at %08lx\n", reg, addr);
#endif /* CONFIG_PRAM */

#if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
	/* reserve TLB table */
	gd->arch.tlb_size = 4096 * 4;
	addr -= gd->arch.tlb_size;

	/* round down to next 64 kB limit */
	addr &= ~(0x10000 - 1);

	gd->arch.tlb_addr = addr;
	debug("TLB table from %08lx to %08lx\n", addr, addr + gd->arch.tlb_size);
#endif

	/* round down to next 4 kB limit */
	addr &= ~(4096 - 1);
	debug("Top of RAM usable for U-Boot at: %08lx\n", addr);

#ifdef CONFIG_LCD
#ifdef CONFIG_FB_ADDR
	gd->fb_base = CONFIG_FB_ADDR;
#else
	/* reserve memory for LCD display (always full pages) */
	addr = lcd_setmem(addr);
	gd->fb_base = addr;
#endif /* CONFIG_FB_ADDR */
#endif /* CONFIG_LCD */

	/*
	 * reserve memory for U-Boot code, data & bss
	 * round down to next 4 kB limit
	 */
	addr -= gd->mon_len;
	addr &= ~(4096 - 1);

	debug("Reserving %ldk for U-Boot at: %08lx\n", gd->mon_len >> 10, addr);

#ifndef CONFIG_SPL_BUILD
	/*
	 * reserve memory for malloc() arena
	 */
	addr_sp = addr - TOTAL_MALLOC_LEN;
	debug("Reserving %dk for malloc() at: %08lx\n",
			TOTAL_MALLOC_LEN >> 10, addr_sp);
	/*
	 * (permanently) allocate a Board Info struct
	 * and a permanent copy of the "global" data
	 */
	addr_sp -= sizeof (bd_t);
	bd = (bd_t *) addr_sp;
	gd->bd = bd;
	debug("Reserving %zu Bytes for Board Info at: %08lx\n",
			sizeof (bd_t), addr_sp);

#ifdef CONFIG_MACH_TYPE
	gd->bd->bi_arch_number = CONFIG_MACH_TYPE; /* board id for Linux */
#endif

	addr_sp -= sizeof (gd_t);
	id = (gd_t *) addr_sp;
	debug("Reserving %zu Bytes for Global Data at: %08lx\n",
			sizeof (gd_t), addr_sp);

#if defined(CONFIG_OF_SEPARATE) && defined(CONFIG_OF_CONTROL)
	/*
	 * If the device tree is sitting immediate above our image then we
	 * must relocate it. If it is embedded in the data section, then it
	 * will be relocated with other data.
	 */
	if (gd->fdt_blob) {
		fdt_size = ALIGN(fdt_totalsize(gd->fdt_blob) + 0x1000, 32);

		addr_sp -= fdt_size;
		new_fdt = (void *)addr_sp;
		debug("Reserving %zu Bytes for FDT at: %08lx\n",
		      fdt_size, addr_sp);
	}
#endif

	/* setup stackpointer for exeptions */
	gd->irq_sp = addr_sp;
#ifdef CONFIG_USE_IRQ
	addr_sp -= (CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ);
	debug("Reserving %zu Bytes for IRQ stack at: %08lx\n",
		CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ, addr_sp);
#endif
	/* leave 3 words for abort-stack    */
	addr_sp -= 12;

	/* 8-byte alignment for ABI compliance */
	addr_sp &= ~0x07;
#else
	addr_sp += 128;	/* leave 32 words for abort-stack   */
	gd->irq_sp = addr_sp;
#endif
	interrupt_init();

	debug("New Stack Pointer is: %08lx\n", addr_sp);

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

	gd->bd->bi_baudrate = gd->baudrate;
	/* Ram ist board specific, so move it to board code ... */
	dram_init_banksize();
	display_dram_config();	/* and display it */

	gd->relocaddr = addr;
	gd->start_addr_sp = addr_sp;
	gd->reloc_off = addr - _TEXT_BASE;
	debug("relocation Offset is: %08lx\n", gd->reloc_off);
	if (new_fdt) {
		memcpy(new_fdt, gd->fdt_blob, fdt_size);
		gd->fdt_blob = new_fdt;
	}
	memcpy(id, (void *)gd, sizeof(gd_t));

• 这一段主要是在做内存分配动作.
  • addr = CONFIG_SYS_SDRAM_BASE + gd->ram_size; 从RAM的顶部地址开始
    
  • LOGBUFF_RESERVE : Reserving %dk for kernel logbuffer
    
  • pram : Reserving %ldk for protected RAM
    
  • tlb_addr: reserve TLB table(16K), 然后会把地址对齐到64K处.
    
  • addr &= ~(4096 - 1): 做完上面的内存分配动作之后, 在保留4KB的空间. 干嘛用还不清楚.
    
  • relocaddr: 在接来下的RAM就是U-boot可以用的了 : Top of RAM usable for U-Boot
  • LCD
    • 如果用户定义了CONFIG_FB_ADDR, 那这里就不为LCD保留显存了
    • 如果用户定义了CONFIG_LCD, 又没有定义CONFIG_FB_ADDR, 则为LCD保留一块显存
  • Code, data, bss : reserve memory for U-Boot code, data & bss
  • malloc : reserve memory for malloc() arena, 突然想起了堆和栈的区别, 网上查了一下, 用户自己分配和释放的属于堆区. 貌似这个地方就是堆区哦.
    
  • bd : Board Info struct
  • gd: Global Data
  • fdt
  • irq_sp : IRQ & FIQ 栈指针. 向下生长
    
  • start_addr_sp : 系统栈指针. 主要是在C函数调用过程中, 函数参数, 返回地址的入栈出栈操作.
    
  • reloc_off : gd->reloc_off = addr - _TEXT_BASE;
    
    • relocate offset, 这里的意思暂时没弄懂
• gd->bd->bi_arch_number = CONFIG_MACH_TYPE; /* board id for Linux */ 这个赋值动作, 记得老版本的uboot是在BOARDDIR下面做的.
  
• dram_init_banksize : 需要在BOARDDIR下面实现, 告诉系统有几块RAM, 每一块的大小是多少.

init_sequence

init_fnc_t *init_sequence[] = {
	arch_cpu_init,		/* basic arch cpu dependent setup */
	mark_bootstage,
#ifdef CONFIG_OF_CONTROL
	fdtdec_check_fdt,
#endif
#if defined(CONFIG_BOARD_EARLY_INIT_F)
	board_early_init_f,
#endif
	timer_init,		/* initialize timer */
#ifdef CONFIG_BOARD_POSTCLK_INIT
	board_postclk_init,
#endif
#ifdef CONFIG_FSL_ESDHC
	get_clocks,
#endif
	env_init,		/* initialize environment */
	init_baudrate,		/* initialze baudrate settings */
	serial_init,		/* serial communications setup */
	console_init_f,		/* stage 1 init of console */
	display_banner,		/* say that we are here */
#if defined(CONFIG_DISPLAY_CPUINFO)
	print_cpuinfo,		/* display cpu info (and speed) */
#endif
#if defined(CONFIG_DISPLAY_BOARDINFO)
	checkboard,		/* display board info */
#endif
#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SYS_I2C)
	init_func_i2c,
#endif
	dram_init,		/* configure available RAM banks */
	NULL,
};

• arch_cpu_init
  
  • 一般厂商会实现, 根据实际需要初始化CPU相关的一些东西
  • 如果没有其他实现, 就会用board.c中的weak实现.
• mark_bootstage
  
  •  Record the board_init_f() bootstage (after arch_cpu_init())
    
• fdtdec_check_fdt : fdt相关, 暂不分析
• board_early_init_f
  
  • 一般在BOARDDIR下面实现, 初始化必要的硬件
• timer_init
  
  • 时钟初始化
• board_postclk_init
  
• get_clocks
  
• env_init
  
  • 以nandflash为例, 此时还没有对nandflash进行初始化, 所以这个函数的实现不会从nand中去读取实际保存的变量. 只是简单标记env_valid为1
  • env_common.c中的env_relocate() will do the real validation
    
• init_baudrate
  
  • 初始化gd->baudrate
  • gd->baudrate = getenv_ulong("baudrate", 10, CONFIG_BAUDRATE);
• serial_init
  
  • uboot的serial子系统相关
• console_init_f
  
  • stage 1 init of console
    
  • Called before relocation - use serial functions
    
• print_cpuinfo
  
  • display cpu info (and speed)
    
• checkboard
  
  • display board info
• dram_init
  
  • 初始化gd->ram_size
    
  • 接下来的code会做内存分配, 需要用到这个值. 注意, 如果有多块DRAM, 起始地址不一样, 那这里的ram_size应该只是其中1块的大小.
    • 比如BANK1: 0x20000000 64M;  BANK2: 0x40000000 64M; 那这个ram_size应该是64M, 而不是128M. 具体原因, 可以看上文中的内存分配动作

board_init_r

gd->flags |= GD_FLG_RELOC;	/* tell others: relocation done */

• 做过relocate之后, 才调用的board_init_r

board_init();	/* Setup chipselects */

• board_init需要在BOARDDIR中实现.

serial_initialize();

• uboot的serial子系统相关. 完成实际的串口初始化工作

/* 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);

• dest_addr是_main的汇编代码传递进来的参数 GD_RELOCADDR.
• GD_RELOCADDR是在board_init_f阶段被赋值的.
  

power_init_board();

• 可以选择性的在BOARDDIR下实现.
• 如果没有实现, 则会使用board.c中的weak实现

nand_init();

• nandflash初始化, 会调用mtd/nand/nand.c中的nand_init

mmc_initialize

• sd卡初始化, 会调用drivers/mmc/mmc.c中的mmc_initialize

env_relocate

• board_init_f->init_sequence中的env_init其实没有做什么实质性动作, 因为当时nand还没有初始化
• 所以这里的env_relocate会调用common/env_common.c中的env_relocate, 继而开始做实质性的env初始动作. 也就是从nandflash中读取我们自己设置的环境变量

stdio_init

• 调用common/stdio.c中的stdio_init, 做一些IO相关的初始化
  • lcd, video, keyboard, nc, jtag等等

jumptable_init

• 调用include/_exports.h中定义的各种通用的操作函数
  • get_version, getc, malloc, udelay等等
    

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

• 控制台最终初始化

#ifdef CONFIG_BOARD_LATE_INIT
	board_late_init();
#endif

• 可以选择性的在BOARDDIR中定义board_late_init, 做一些最后的初始化动作

#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

• 在BOARDDIR中实现eth_initialize, 初始化网络
• 在BOARDDIR中实现reset_phy, 复位phy. 

	for (;;) {
		main_loop();
	}

• 进入common/main.c中的main_loop
  • 如果没有按下空格键, uboot会执行bootcmd中的命令
  • 如果按下空格键, 则会进入控制台, 与用户交互, 执行命令

总结

stage1 vs stage2

stage1也就是SPL, stage2也就是本篇所指的u-boot.bin, 主要有以下不同点

• u-boot.bin在start.S中会对异常中断进行响应
• u-boot.bin中的board_init_f实现与SPL阶段不一样
• u-boot.bin中的board_init_r实现与SPL阶段不一样

global_data

u-boot.bin会对全局数据gd先清理, 然后在重新初始化.

需要实现的函数

• dram_init_banksize:  BOARDDIR下实现
  
  • 告诉系统有几块RAM, 每一块的大小是多少.
• board_early_init_f : BOARDDIR下实现
  
• board_init : BOARDDIR下实现
  
• eth_initialize : BOARDDIR下实现