Androidソースコンパイル(三)-------->beagleboard-xm u-boot

   1: make CROSS_COMPILE=arm-none-linux-gnueabi- mrproper

   2: make CROSS_COMPILE=arm-none-linux-gnueabi- omap3_beagle_config

   3: make CROSS_COMPILE=arm-none-linux-gnueabi- 

   1: #

   2: # Physical Address:

   3: # 8000'0000 (bank0)

   4: # A000/0000 (bank1)

   5: # Linux-Kernel is expected to be at 8000'8000, entry 8000'8000

   6: # (mem base + reserved)

   7:  

   8: # For use with external or internal boots.

   9: CONFIG_SYS_TEXT_BASE = 0x80008000

CONFIG_SYS_TEXT_BASE as macro passed into build options as:
arm-none-linux-gnueabi-gcc   -D__ASSEMBLY__ -g  -Os   -fno-common -ffixed-r8 -msoft-float   -D__KERNEL__-DCONFIG_SYS_TEXT_BASE=0×80008000 -I/home/ken/bb/u-boot/u-boot-mailine/include -fno-builtin -ffreestanding -nostdinc -isystem/opt/sourcery_g++/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.3/include -pipe  -DCONFIG_ARM -D__ARM__ -marm  -mabi=aapcs-linux -mno-thumb-interwork -march=armv5   -o start.o start.S –c
(BTW: there is some interesting compiler options used: –ffreestanding, –isystem, –mabi=aapcs-linux)
It is worth to mention that uboot will keep some information into a global_data in top of stack, the structure is defined in uboot\arch\arm\include\asm\global_data.h:

   1: typedef    struct    global_data {

   2:     bd_t        *bd;

   3:     unsigned long    flags;

   4:     unsigned long    baudrate;

   5:     unsigned long    have_console;    /* serial_init() was called */

   6:     unsigned long    env_addr;    /* Address  of Environment struct */

   7:     unsigned long    env_valid;    /* Checksum of Environment valid? */

   8:     unsigned long    fb_base;    /* base address of frame buffer */

   9: #ifdef CONFIG_VFD

  10:     unsigned char    vfd_type;    /* display type */

  11: #endif

  12: #ifdef CONFIG_FSL_ESDHC

  13:     unsigned long    sdhc_clk;

  14: #endif

  15: #ifdef CONFIG_AT91FAMILY

  16:     /* "static data" needed by at91's clock.c */

  17:     unsigned long    cpu_clk_rate_hz;

  18:     unsigned long    main_clk_rate_hz;

  19:     unsigned long    mck_rate_hz;

  20:     unsigned long    plla_rate_hz;

  21:     unsigned long    pllb_rate_hz;

  22:     unsigned long    at91_pllb_usb_init;

  23: #endif

  24: #ifdef CONFIG_ARM

  25:     /* "static data" needed by most of timer.c on ARM platforms */

  26:     unsigned long    timer_rate_hz;

  27:     unsigned long    tbl;

  28:     unsigned long    tbu;

  29:     unsigned long long    timer_reset_value;

  30:     unsigned long    lastinc;

  31: #endif

  32:     unsigned long    relocaddr;    /* Start address of U-Boot in RAM */

  33:     phys_size_t    ram_size;    /* RAM size */

  34:     unsigned long    mon_len;    /* monitor len */

  35:     unsigned long    irq_sp;        /* irq stack pointer */

  36:     unsigned long    start_addr_sp;    /* start_addr_stackpointer */

  37:     unsigned long    reloc_off;

  38: #if !(defined(CONFIG_SYS_NO_ICACHE) && defined(CONFIG_SYS_NO_DCACHE))

  39:     unsigned long    tlb_addr;

  40: #endif

  41:     void        **jt;        /* jump table */

  42:     char        env_buf[32];    /* buffer for getenv() before reloc. */

  43: } gd_t;

   1: #

   2: # Physical Address:

   3: # 8000'0000 (bank0)

   4: # A000/0000 (bank1)

   5: # Linux-Kernel is expected to be at 8000'8000, entry 8000'8000

   6: # (mem base + reserved)

   7:  

   8: # For use with external or internal boots.

   9: CONFIG_SYS_TEXT_BASE = 0x80008000

 
   
80008000 T _start

80008020 t _undefined_instruction

80008024 t _software_interrupt

80008028 t _prefetch_abort

8000802c t _data_abort

80008030 t _not_used

80008034 t _irq

80008038 t _fiq
  
 
  

   1: mrs    r0, cpsr

   2: bic    r0, r0, #0x1f

   3: orr    r0, r0, #0xd3

   4: msr    cpsr,r0

   1: #define CONFIG_SYS_INIT_RAM_ADDR    0x4020f800

   2: #define CONFIG_SYS_INIT_RAM_SIZE    0x800

   3: #define CONFIG_SYS_INIT_SP_ADDR        (CONFIG_SYS_INIT_RAM_ADDR + \

   4:                      CONFIG_SYS_INIT_RAM_SIZE - \

   5:                      GENERATED_GBL_DATA_SIZE)

 

As above mentioned, before top of stack, global_data will be stored, the size of global_data is determined/generated at build time (include\generated\generic-asm-offices.h)

   1: #define GENERATED_GBL_DATA_SIZE (128) /* (sizeof(struct global_data) + 15) & ~15 */
  
 Call C function board_init_f (uboot\arch\arm\lib\board.c): 
 Assign/Init global data structure at 0x4020F800 
  
 Disable memory I/O cache for compiler optization, just like MemoryFence() used in edk2 MdePkg: 
  
  
   1: __asm__ __volatile__("": : :"memory");