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;