UU-boot和kernel的传参
bd_info
```u-boot.h
typedefstruct bd_info {
int bi_baudrate;/* serial console baudrate */
unsignedlong bi_ip_addr;/* IP Address */
struct environment_s *bi_env;
ulong bi_arch_number;/* unique id for this board */
ulong bi_boot_params;/* where this board expects params */
struct/* RAM configuration */
{
ulong start;
ulong size;
} bi_dram[CONFIG_NR_DRAM_BANKS];
}bd_t;
#define bi_env_data bi_env->data
#define bi_env_crc bi_env->crc
```