uboot的gd_t和bd_t数据结构

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gd_tbd_tu-boot中两个重要的数据结构,在初始化操作很多都要靠这两个数据结构来保存或传递。分别定义在./include/asm-arm/global_data.h ./include/asm-arm/u-boot.h

1gd_t : global data数据结构定义,位于文件 include/asm-arm/global_data.h。其成员主要是一些全局的系统初始化参数。当使用gd_t时需用宏定义进行声明:DECLARE_GLOBAL_DATA_PTR,指定占用寄存器R8

/*
* The following data structure is placed in some memory wich is
* available very early after boot (like DPRAM on MPC8xx/MPC82xx, or
* some locked parts of the data cache) to allow for a minimum set of
* global variables during system initialization (until we have set
* up the memory controller so that we can use RAM).
*
* Keep it *SMALL* and remember to set CFG_GBL_DATA_SIZE > sizeof(gd_t)
* CFG_GBL_DATA_SIZE
config文件中定义,start.S中会根据这个值分配栈空间给global_data
*/


typedef    struct    global_data {
    bd_t           *bd;                        
// struct board_info
指针,保存板子信息
    unsigned long    flags;                      
// 指示标志,如设备已经初始化标志等
    unsigned long    baudrate;                 
// 串口波特率
    unsigned long    have_console;          
// 串口初始化标志
    unsigned long    env_addr;                // Address of Environment struct ,环境参数地址
    unsigned long    env_valid;               // 环境参数CRC检验有效标志
    unsigned long    fb_base;                  // frame buffer的基址
#ifdef CONFIG_VFD
    unsigned char    vfd_type;                
/* display type */
#endif
#if 0
    unsigned long    cpu_clk;                 
/* CPU clock in Hz! */
    unsigned long    bus_clk;
    unsigned long    ram_size;                
/* RAM size */
    unsigned long    reset_status;            
/* reset status register at boot */
#endif
    void        **jt;                              
/* jump table */
} gd_t;


/*
* Global Data Flags
*/


#define    GD_FLG_RELOC         0x00001         /* Code was relocated to RAM */
#define    GD_FLG_DEVINIT      0x00002         /* Devices have been initialized */

#define    GD_FLG_SILENT        0x00004         
/* Silent mode */
#define    GD_FLG_POSTFAIL    0x00008
         /* Critical POST test failed           */

#define    GD_FLG_POSTSTOP   0x00010         /* POST seqeunce aborted           */

#define    GD_FLG_LOGINIT      0x00020         /* Log Buffer has been initialized   */

#define   GD_FLG_DISABLE_CONSOLE   0x00040         /* Disable console (in & out) */
#define DECLARE_GLOBAL_DATA_PTR     register volatile gd_t *gd asm ("r8")


2.bd_t :board info数据结构定义,位于文件 include/asm-arm/u-boot.h。保存板子参数。

typedef struct bd_info {
    int                         bi_baudrate;                  /
串口波特率
    unsigned long         bi_ip_addr;                   
// IP地址
    struct environment_s     *bi_env;
    ulong                    bi_arch_number;           
// 板子ID
    ulong                    bi_boot_params;            
// 启动参数
    struct                                         
// DRAM BANKS配置,起始地址与长度
    {
    ulong      start;
    ulong      size;
    }bi_dram[CONFIG_NR_DRAM_BANKS];
} bd_t;

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