bd_t和gd_t是u-boot中兩個重要的數據結構，初始化操作中很多全局變量都要靠這兩個數據結構來保存或傳遞。

分別定義在include/asm-arm/u-boot.h和include/asm-arm/global_data.h中。

一、bd_t?

（1）board info數據結構定義，主要是用來保存板子參數。

（2）結構體定義

typedef struct bd_info {int bi_baudrate; /* serial console baudrate */unsigned long bi_ip_addr; /* IP Address *//*開發板ID，該變量標識每一種開發板相關的ID，該值將傳遞給內核；如果這個參數與內核配置的不相同，那么內核啟動解壓縮完成后將出現“Error : a”錯誤；開發板ID可以在內核arch / arm / tools / mach - types中查看 */ulong bi_arch_number; /* unique id for this board*/ulong bi_boot_params; /* where this board expects params u-boot傳遞給內核的參數的保存地址*/struct /* RAM configuration 內存的起始地址及大小 */{ulong start;ulong size;} bi_dram[CONFIG_NR_DRAM_BANKS];} bd_t;
二、gd_t?

（1）global data數據結構定義，其成員主要是一些全局的系統初始化參數。當使用gd_t時需用宏定義進行聲明：DECLARE_GLOBAL_DATA_PTR，指定占用寄存器R8。

（2）結構體定義

typedef struct global_data {bd_t *bd; //與板子相關的結構，同上unsigned long flags; //指示標志，如設備已經初始化標志等unsigned long baudrate; //串口波特率unsigned long have_console; /* serial_init() was called */ //串口初始化標志#ifdef CONFIG_PRE_CONSOLE_BUFFER //宏未定義unsigned long precon_buf_idx; /* Pre-Console buffer index */#endifunsigned long env_addr; /* Address of Environment struct */ //環境變量參數地址unsigned long env_valid; /* Checksum of Environment valid? */ //檢驗環境變量參數是否有效unsigned long fb_base; /* base address of frame buffer */ // frame buffer基址#ifdef CONFIG_FSL_ESDHC //宏未在板子相關頭文件中定義unsigned long sdhc_clk;#endif#ifdef CONFIG_AT91FAMILY //宏未在板子相關頭文件中定義/* "static data" needed by at91's clock.c */unsigned long cpu_clk_rate_hz;unsigned long main_clk_rate_hz;unsigned long mck_rate_hz;unsigned long plla_rate_hz;unsigned long pllb_rate_hz;unsigned long at91_pllb_usb_init;#endif#ifdef CONFIG_ARM //宏未定義/* "static data" needed by most of timer.c on ARM platforms */unsigned long timer_rate_hz;unsigned long tbl;unsigned long tbu;unsigned long long timer_reset_value;unsigned long lastinc;#endif#ifdef CONFIG_IXP425 //宏未在板子相關頭文件中定義unsigned long timestamp;#endifunsigned long relocaddr; /* Start address of U-Boot in RAM */ //u-boot自搬移至內存后的起始地址phys_size_t ram_size; /* RAM size */unsigned long mon_len; /* monitor len */unsigned long irq_sp; /* irq stack pointer */unsigned long start_addr_sp; /* start_addr_stackpointer */unsigned long reloc_off;#if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF)) //宏未定義unsigned long tlb_addr;#endifconst void *fdt_blob; /* Our device tree, NULL if none */void **jt; /* jump table */char env_buf[32]; /* buffer for getenv() before reloc. */#if defined(CONFIG_POST) || defined(CONFIG_LOGBUFFER) //宏未定義unsigned long post_log_word; /* Record POST activities */unsigned long post_log_res; /* success of POST test */unsigned long post_init_f_time; /* When post_init_f started */#endif }gd_t;

總結

以上是生活随笔為你收集整理的uboot源码——gd_t和bd_t数据结构的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。