Global data¶
Globally required fields are held in the global data structure. A pointer to the structure is available as symbol gd. The symbol is made available by the macro %DECLARE_GLOBAL_DATA_PTR.
Register pointing to global data¶
On most architectures the global data pointer is stored in a register.
ARC | r25 |
ARM 32bit | r9 |
ARM 64bit | x18 |
M68000 | d7 |
MicroBlaze | r31 |
NDS32 | r10 |
Nios II | gp |
PowerPC | r2 |
RISC-V | gp (x3) |
SuperH | r13 |
x86 32bit | fs |
The sandbox, x86_64, and Xtensa are notable exceptions.
Clang for ARM does not support assigning a global register. When using Clang gd is defined as an inline function using assembly code. This adds a few bytes to the code size.
Binaries called by U-Boot are not aware of the register usage and will not conserve gd. UEFI binaries call the API provided by U-Boot and may return to U-Boot. The value of gd has to be saved every time U-Boot is left and restored whenever U-Boot is reentered. This is also relevant for the implementation of function tracing. For setting the value of gd function set_gd() can be used.
Global data structure¶
-
struct
global_data
¶ global data structure
Definition
struct global_data {
struct bd_info *bd;
unsigned long flags;
unsigned int baudrate;
unsigned long cpu_clk;
unsigned long bus_clk;
unsigned long pci_clk;
unsigned long mem_clk;
#if defined(CONFIG_LCD) || defined(CONFIG_VIDEO) || defined(CONFIG_DM_VIDEO);
unsigned long fb_base;
#endif;
#if defined(CONFIG_POST);
unsigned long post_log_word;
unsigned long post_log_res;
unsigned long post_init_f_time;
#endif;
#ifdef CONFIG_BOARD_TYPES;
unsigned long board_type;
#endif;
unsigned long have_console;
#if CONFIG_IS_ENABLED(PRE_CONSOLE_BUFFER);
unsigned long precon_buf_idx;
#endif;
unsigned long env_addr;
unsigned long env_valid;
unsigned long env_has_init;
int env_load_prio;
unsigned long ram_base;
phys_addr_t ram_top;
unsigned long relocaddr;
phys_size_t ram_size;
unsigned long mon_len;
unsigned long irq_sp;
unsigned long start_addr_sp;
unsigned long reloc_off;
struct global_data *new_gd;
#ifdef CONFIG_DM;
unsigned long dm_flags;
struct udevice *dm_root;
struct udevice *dm_root_f;
struct list_head uclass_root_s;
struct list_head *uclass_root;
# if CONFIG_IS_ENABLED(OF_PLATDATA);
struct driver_rt *dm_driver_rt;
# endif;
#endif;
#ifdef CONFIG_TIMER;
struct udevice *timer;
#endif;
const void *fdt_blob;
void *new_fdt;
unsigned long fdt_size;
#if CONFIG_IS_ENABLED(OF_LIVE);
struct device_node *of_root;
#endif;
#if CONFIG_IS_ENABLED(MULTI_DTB_FIT);
const void *multi_dtb_fit;
#endif;
struct jt_funcs *jt;
char env_buf[32];
#ifdef CONFIG_TRACE;
void *trace_buff;
#endif;
#if defined(CONFIG_SYS_I2C);
int cur_i2c_bus;
#endif;
unsigned int timebase_h;
unsigned int timebase_l;
#if CONFIG_VAL(SYS_MALLOC_F_LEN);
unsigned long malloc_base;
unsigned long malloc_limit;
unsigned long malloc_ptr;
#endif;
#ifdef CONFIG_PCI;
struct pci_controller *hose;
phys_addr_t pci_ram_top;
#endif;
#ifdef CONFIG_PCI_BOOTDELAY;
int pcidelay_done;
#endif;
struct udevice *cur_serial_dev;
struct arch_global_data arch;
#ifdef CONFIG_CONSOLE_RECORD;
struct membuff console_out;
struct membuff console_in;
#endif;
#ifdef CONFIG_DM_VIDEO;
ulong video_top;
ulong video_bottom;
#endif;
#ifdef CONFIG_BOOTSTAGE;
struct bootstage_data *bootstage;
struct bootstage_data *new_bootstage;
#endif;
#ifdef CONFIG_LOG;
int log_drop_count;
int default_log_level;
struct list_head log_head;
int log_fmt;
bool processing_msg;
int logc_prev;
int logl_prev;
#endif;
#if CONFIG_IS_ENABLED(BLOBLIST);
struct bloblist_hdr *bloblist;
struct bloblist_hdr *new_bloblist;
#endif;
#if CONFIG_IS_ENABLED(HANDOFF);
struct spl_handoff *spl_handoff;
#endif;
#if defined(CONFIG_TRANSLATION_OFFSET);
fdt_addr_t translation_offset;
#endif;
#if CONFIG_IS_ENABLED(WDT);
struct udevice *watchdog_dev;
#endif;
#ifdef CONFIG_GENERATE_ACPI_TABLE;
struct acpi_ctx *acpi_ctx;
#endif;
#if CONFIG_IS_ENABLED(GENERATE_SMBIOS_TABLE);
char *smbios_version;
#endif;
};
Members
bd
- board information
flags
global data flags
See
enum gd_flags
baudrate
- baud rate of the serial interface
cpu_clk
- CPU clock rate in Hz
bus_clk
- platform clock rate in Hz
pci_clk
- PCI clock rate in Hz
mem_clk
- memory clock rate in Hz
fb_base
- base address of frame buffer memory
post_log_word
active POST tests
post_log_word is a bit mask defining which POST tests are recorded (see constants POST_*).
post_log_res
POST results
post_log_res is a bit mask with the POST results. A bit with value 1 indicates successful execution.
post_init_f_time
- time in ms when post_init_f() started
board_type
board type
If a U-Boot configuration supports multiple board types, the actual board type may be stored in this field.
have_console
console is available
A value of 1 indicates that serial_init() was called and a console is available. A value of 0 indicates that console input and output drivers shall not be called.
precon_buf_idx
pre-console buffer index
precon_buf_idx indicates the current position of the buffer used to collect output before the console becomes available
env_addr
address of environment structure
env_addr contains the address of the structure holding the environment variables.
env_valid
environment is valid
See
enum env_valid
env_has_init
bit mask indicating environment locations
enum env_location
defines which bit relates to which locationenv_load_prio
- priority of the loaded environment
ram_base
- base address of RAM used by U-Boot
ram_top
- top address of RAM used by U-Boot
relocaddr
start address of U-Boot in RAM
After relocation this field indicates the address to which U-Boot has been relocated. It can be displayed using the bdinfo command. Its value is needed to display the source code when debugging with GDB using the ‘add-symbol-file u-boot <relocaddr>’ command.
ram_size
- RAM size in bytes
mon_len
- monitor length in bytes
irq_sp
- IRQ stack pointer
start_addr_sp
- initial stack pointer address
reloc_off
- relocation offset
new_gd
- pointer to relocated global data
dm_flags
additional flags for Driver Model
See
enum gd_dm_flags
dm_root
- root instance for Driver Model
dm_root_f
- pre-relocation root instance
uclass_root_s
head of core tree when uclasses are not in read-only memory.
When uclasses are in read-only memory, uclass_root_s is not used and uclass_root points to the root node generated by dtoc.
uclass_root
pointer to head of core tree, if uclasses are in read-only memory and cannot be adjusted to use uclass_root as a list head.
When not in read-only memory, uclass_root_s is used to hold the uclass root, and uclass_root points to the address of uclass_root_s.
dm_driver_rt
- Dynamic info about the driver
timer
- timer instance for Driver Model
fdt_blob
- U-Boot’s own device tree, NULL if none
new_fdt
- relocated device tree
fdt_size
- space reserved for relocated device space
of_root
- root node of the live tree
multi_dtb_fit
- pointer to uncompressed multi-dtb FIT image
jt
jump table
The jump table contains pointers to exported functions. A pointer to the jump table is passed to standalone applications.
env_buf
- buffer for env_get() before reloc
trace_buff
trace buffer
When tracing function in U-Boot this field points to the buffer recording the function calls.
cur_i2c_bus
- currently used I2C bus
timebase_h
- high 32 bits of timer
timebase_l
- low 32 bits of timer
malloc_base
- base address of early malloc()
malloc_limit
- limit address of early malloc()
malloc_ptr
- current address of early malloc()
hose
- PCI hose for early use
pci_ram_top
- top of region accessible to PCI
pcidelay_done
delay time before scanning of PIC hose expired
If CONFIG_PCI_BOOTDELAY=y, pci_hose_scan() waits for the number of milliseconds defined by environment variable pcidelay before scanning. Once this delay has expired the flag pcidelay_done is set to 1.
cur_serial_dev
- current serial device
arch
- architecture-specific data
console_out
output buffer for console recording
This buffer is used to collect output during console recording.
console_in
input buffer for console recording
If console recording is activated, this buffer can be used to emulate input.
video_top
- top of video frame buffer area
video_bottom
- bottom of video frame buffer area
bootstage
- boot stage information
new_bootstage
- relocated boot stage information
log_drop_count
number of dropped log messages
This counter is incremented for each log message which can not be processed because logging is not yet available as signaled by flag
GD_FLG_LOG_READY
in flags.default_log_level
default logging level
For logging devices without filters default_log_level defines the logging level, cf.
enum log_level_t
.log_head
- list of logging devices
log_fmt
bit mask for logging format
The log_fmt bit mask selects the fields to be shown in log messages.
enum log_fmt
defines the bits of the bit mask.processing_msg
a log message is being processed
This flag is used to suppress the creation of additional messages while another message is being processed.
logc_prev
logging category of previous message
This value is used as logging category for continuation messages.
logl_prev
logging level of the previous message
This value is used as logging level for continuation messages.
bloblist
- blob list information
new_bloblist
- relocated blob list information
spl_handoff
- SPL hand-off information
translation_offset
optional translation offset
See CONFIG_TRANSLATION_OFFSET.
watchdog_dev
- watchdog device
acpi_ctx
- ACPI context pointer
smbios_version
- Points to SMBIOS type 0 version
-
gd_board_type
()¶ retrieve board type
Parameters
Return
global board type
-
enum
gd_flags
¶ global data flags
Constants
GD_FLG_RELOC
- code was relocated to RAM
GD_FLG_DEVINIT
- devices have been initialized
GD_FLG_SILENT
- silent mode
GD_FLG_POSTFAIL
- critical POST test failed
GD_FLG_POSTSTOP
- POST sequence aborted
GD_FLG_LOGINIT
- log Buffer has been initialized
GD_FLG_DISABLE_CONSOLE
- disable console (in & out)
GD_FLG_ENV_READY
- environment imported into hash table
GD_FLG_SERIAL_READY
- pre-relocation serial console ready
GD_FLG_FULL_MALLOC_INIT
- full malloc() is ready
GD_FLG_SPL_INIT
- spl_init() has been called
GD_FLG_SKIP_RELOC
- don’t relocate
GD_FLG_RECORD
- record console
GD_FLG_ENV_DEFAULT
- default variable flag
GD_FLG_SPL_EARLY_INIT
- early SPL initialization is done
GD_FLG_LOG_READY
- log system is ready for use
GD_FLG_WDT_READY
- watchdog is ready for use
GD_FLG_SKIP_LL_INIT
- don’t perform low-level initialization
GD_FLG_SMP_READY
- SMP initialization is complete
Description
See field flags of struct global_data
.
-
enum
gd_dm_flags
¶ global data flags for Driver Model
Constants
GD_DM_FLG_SIZE_CELLS_0
- Enable #size-cells=<0> translation
Description
See field dm_flags of struct global_data
.