u-boot第二阶段之gd_t和 bd_t结构体

1）、

typedef    struct    global_data {

    bd_t        *bd; //与板子相关的结构，见下面
    unsigned long    flags;
    unsigned long    baudrate;   //波特率
    unsigned long    have_console;    /* serial_init() was called */
    unsigned long    reloc_off;    /* Relocation Offset,重定位偏移 */
    unsigned long    env_addr;    /* Address  of Environment struct ,存放环境变量结构的地址*/
    unsigned long    env_valid;    /* Checksum of Environment valid? */
#ifdef CONFIG_VFD  //我们一般没有配置这个，这个是frame buffer的首地址
    unsigned long    fb_base;    /* base address of frame buffer,真缓冲器的基 基址*/
#endif
#if 0
unsigned long cpu_clk; /* CPU clock in Hz! CPU的时钟频率*/
unsigned long bus_clk; //总线的时钟频率
unsigned long ram_size; /* RAM size, RAM的大小*/
unsigned long reset_status; /* reset status register at boot */
#endif
void  **jt;  /* jump table ,保存着些函数的入口地址,在common/Exports.c中进行填充*/
} gd_t;

2）、

typedef struct bd_info {
int bi_baudrate;/* serial console baudrate */

unsigned long bi_ip_addr;/* IP Address */

unsigned char bi_enetaddr[6];/* Ethernet adress （MAC地址）*/

unsigned long bi_arch_number;/* unique id for this board 开发板ID 该变量标识每一种开发板相关的ID，该值将传递给内核，如果这个参数与内核配置的不相同，那么内核启动解压缩完成后将出现“Error:a”错误*/

unsigned long bi_boot_params;/* where this board expects params U-boot传递给linux内核的参数保存地址*/

unsigned long bi_memstart;/* start of DRAM memory */

unsigned long bi_memsize;/* size  of DRAM memory in bytes */

unsigned long bi_flashstart;/* start of FLASH memory */

unsigned long bi_flashsize;/* size  of FLASH memory */

unsigned long bi_flashoffset;/* reserved area for startup monitor */

} bd_t;