u-boot bl_main分析

Posted 2022-12-22 idyllcheung

ldr    r0, =(CONFIG_SYS_INIT_SP_ADDR)：

#define CONFIG_SYS_INIT_SP_ADDR     (CONFIG_SYS_INIT_RAM_ADDR + \
                    CONFIG_SYS_INIT_RAM_SIZE - GENERATED_GBL_DATA_SIZE)

#define CONFIG_SYS_INIT_RAM_ADDR    0x20000

#define CONFIG_SYS_INIT_RAM_SIZE    0x30000

GENERATED_GBL_DATA_SIZE宏定义，它是由DEFINE(GENERATED_GBL_DATA_SIZE,(sizeof(struct global_data) + 15) & ~15);获得的，也就是相当于#define GENERATED_GBL_DATA_SIZE ((sizeof(struct global_data) + 15) & ~15)。

 

 

bl    board_init_f_alloc_reserve (参数CONFIG_SYS_INIT_SP_ADDR)：

ulong board_init_f_alloc_reserve(ulong top)

    /* Reserve early malloc arena */
#if CONFIG_VAL(SYS_MALLOC_F_LEN)    #0x800
    top -= CONFIG_VAL(SYS_MALLOC_F_LEN);  # -0x800
#endif
    /* LAST : reserve GD (rounded up to a multiple of 16 bytes) */
    top = rounddown(top-sizeof(struct global_data), 16); # -global_data

    return top;

 

board_init_f_init_reserve （参数top）：

void board_init_f_init_reserve(ulong base)

    struct global_data *gd_ptr;

    /*
     * clear GD entirely and set it up.
     * Use gd_ptr, as gd may not be properly set yet.
     */

    gd_ptr = (struct global_data *)base;
    /* zero the area */
    memset(gd_ptr, ‘\0‘, sizeof(*gd));
    /* set GD unless architecture did it already */
#if !defined(CONFIG_ARM)
    arch_setup_gd(gd_ptr);
#endif
    /* next alloc will be higher by one GD plus 16-byte alignment */
    base += roundup(sizeof(struct global_data), 16);

    /*
     * record early malloc arena start.
     * Use gd as it is now properly set for all architectures.
     */

#if CONFIG_VAL(SYS_MALLOC_F_LEN)
    /* go down one ‘early malloc arena‘ */
    gd->malloc_base = base;
    /* next alloc will be higher by one ‘early malloc arena‘ size */
    base += CONFIG_VAL(SYS_MALLOC_F_LEN);
#endif

 

    mov    r0, #0
    bl    board_init_f

以board_init_f和board_init_r两个板级的初始化接口为例，u-boot分别在common/board_f.c和common/board_r.c两个文件中提供了通用实现。查看common/Makefile可知：

ifndef CONFIG_SPL_BUILD

# # boards
obj-y += board_f.o
obj-y += board_r.o

endif # !CONFIG_SPL_BUILD