1
u-boot
/u-boot-2018.07-fmxx/include/config.h
/* Automatically generated - do not edit */
#define CONFIG_BOARDDIR board/fmxx/fmql
#include <config_defaults.h>
#include <config_uncmd_spl.h>
#include <configs/fmxx-common.h>
#include <asm/config.h>
#include <linux/kconfig.h>
#include <config_fallbacks.h>
就在想尖括号中的h文件都在哪里搜索
于是去Makefile中找找看线索：
搜索INCLUDE，找到了
UBOOTINCLUDE :=
-Iinclude
$(if $(KBUILD_SRC), -I$(srctree)/include)
$(if $(CONFIG_$(SPL_)SYS_THUMB_BUILD),
$(if $(CONFIG_HAS_THUMB2),,
-I$(srctree)/arch/$(ARCH)/thumb1/include),)
-I$(srctree)/arch/$(ARCH)/include
-include $(srctree)/include/linux/kconfig.h
gcc –o main –I../include -DDebug –g main.c
输出文件 头文件搜索目录 定义宏 用于调试 源文件
–I../include 头文件搜索目录
-I dir 在dir这个目录寻找被include的文
件
2
gd_t结构体在哪里定义呢
u-boot-2018.07-fmxx/common/board_r.c
中用到了DECLARE_GLOBAL_DATA_PTR
DECLARE_GLOBAL_DATA_PTR在arch/arm/include/asm/global_data.h中定义
#include <asm-generic/global_data.h>
#ifdef CONFIG_ARM64
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("x18")
#else
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r9")
#endif
gd_t在u-boot-2018.07-fmxx/include/asm-generic/global_data.h中定义
typedef struct global_data {
bd_t *bd;
unsigned long flags;
unsigned int baudrate;
unsigned long cpu_clk; /* CPU clock in Hz! */
unsigned long bus_clk;
/* We cannot bracket this with CONFIG_PCI due to mpc5xxx */
unsigned long pci_clk;
unsigned long mem_clk;
#if defined(CONFIG_LCD) || defined(CONFIG_VIDEO)
unsigned long fb_base; /* Base address of framebuffer mem */
#endif
#if defined(CONFIG_POST)
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
#ifdef CONFIG_BOARD_TYPES
unsigned long board_type;
#endif
unsigned long have_console; /* serial_init() was called */
#if CONFIG_IS_ENABLED(PRE_CONSOLE_BUFFER)
unsigned long precon_buf_idx; /* Pre-Console buffer index */
#endif
unsigned long env_addr; /* Address of Environment struct */
unsigned long env_valid; /* Environment valid? enum env_valid */
unsigned long env_has_init; /* Bitmask of boolean of struct env_location offsets */
int env_load_location;
unsigned long ram_top; /* Top address of RAM used by U-Boot */
unsigned long relocaddr; /* Start address of U-Boot in RAM */
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;
struct global_data *new_gd; /* relocated global data */
#ifdef CONFIG_DM
struct udevice *dm_root; /* Root instance for Driver Model */
struct udevice *dm_root_f; /* Pre-relocation root instance */
struct list_head uclass_root; /* Head of core tree */
#endif
#ifdef CONFIG_TIMER
struct udevice *timer; /* Timer instance for Driver Model */
#endif
const void *fdt_blob; /* Our device tree, NULL if none */
void *new_fdt; /* Relocated FDT */
unsigned long fdt_size; /* Space reserved for relocated FDT */
#ifdef CONFIG_OF_LIVE
struct device_node *of_root;
#endif
struct jt_funcs *jt; /* jump table */
char env_buf[32]; /* buffer for env_get() before reloc. */
#ifdef CONFIG_TRACE
void *trace_buff; /* The trace buffer */
#endif
#if defined(CONFIG_SYS_I2C)
int cur_i2c_bus; /* current used i2c bus */
#endif
#ifdef CONFIG_SYS_I2C_MXC
void *srdata[10];
#endif
unsigned int timebase_h;
unsigned int timebase_l;
#if CONFIG_VAL(SYS_MALLOC_F_LEN)
unsigned long malloc_base; /* base address of early malloc() */
unsigned long malloc_limit; /* limit address */
unsigned long malloc_ptr; /* current address */
#endif
#ifdef CONFIG_PCI
struct pci_controller *hose; /* PCI hose for early use */
phys_addr_t pci_ram_top; /* top of region accessible to PCI */
#endif
#ifdef CONFIG_PCI_BOOTDELAY
int pcidelay_done;
#endif
struct udevice *cur_serial_dev; /* current serial device */
struct arch_global_data arch; /* architecture-specific data */
#ifdef CONFIG_CONSOLE_RECORD
struct membuff console_out; /* console output */
struct membuff console_in; /* console input */
#endif
#ifdef CONFIG_DM_VIDEO
ulong video_top; /* Top of video frame buffer area */
ulong video_bottom; /* Bottom of video frame buffer area */
#endif
#ifdef CONFIG_BOOTSTAGE
struct bootstage_data *bootstage; /* Bootstage information */
struct bootstage_data *new_bootstage; /* Relocated bootstage info */
#endif
#ifdef CONFIG_LOG
int log_drop_count; /* Number of dropped log messages */
int default_log_level; /* For devices with no filters */
struct list_head log_head; /* List of struct log_device */
int log_fmt; /* Mask containing log format info */
#endif
} gd_t;
3
1.2.2 create_symlink的规则
# symbolic links
# If arch/$(ARCH)/mach-$(SOC)/include/mach exists,
# make a symbolic link to that directory.
# Otherwise, create a symbolic link to arch/$(ARCH)/include/asm/arch-$(SOC).
PHONY += create_symlink
create_symlink:
ifdef CONFIG_CREATE_ARCH_SYMLINK
ifneq ($(KBUILD_SRC),)
$(Q)mkdir -p include/asm
$(Q)if [ -d $(KBUILD_SRC)/arch/$(ARCH)/mach-$(SOC)/include/mach ]; then
dest=arch/$(ARCH)/mach-$(SOC)/include/mach;
else
dest=arch/$(ARCH)/include/asm/arch-$(if $(SOC),$(SOC),$(CPU));
fi;
ln -fsn $(KBUILD_SRC)/$$dest include/asm/arch
else
$(Q)if [ -d arch/$(ARCH)/mach-$(SOC)/include/mach ]; then
dest=../../mach-$(SOC)/include/mach;
else
dest=arch-$(if $(SOC),$(SOC),$(CPU));
fi;
ln -fsn $$dest arch/$(ARCH)/include/asm/arch
endif
endif
注释已经很好解释了create_symlink的行为：
如果arch/$(ARCH)/mach-$(SOC)/include/mach存在，则生成符号链接：arch/$(ARCH)/include/asm/arch --> arch/$(ARCH)/mach-$(SOC)/include/mach
否则生成符号链接arch/$(ARCH)/include/asm/arch --> arch/$(ARCH)/include/asm/arch-$(if $(SOC),$(SOC),$(CPU));
对基于arm v7架构的bcm2837芯片，arch/arm/math-bcm283x文件夹存在，所以生成链接：
arch/arm/include/asm/arch --> arch/arm/mach-bcm283x/include/mach
简单说来，create_symlink就是将芯片指定的arch/$(ARCH)math-$(SOC)连接到跟芯片名字无关的arch/$(ARCH)/include/asm下。