Kernel startup, the millisecond uptime clock, and heap usage. More...

Collaboration diagram for Kernel:

Data Structures
struct	k_heap_stats_t
	Heap usage snapshot filled by k_heap_stats(). More...

struct	k_stack_stats_t
	Main-stack usage filled by k_stack_stats(). More...

Functions
void	k_init (void)
	Initialize kernel services and the standard streams.

Uptime
void	k_uptime_init (void)
	Start the 1 kHz system timer and register `/dev/uptime`.

uint64_t	k_uptime_ms (void)
	Read the uptime clock.

void	k_tick (void)
	Advance the uptime clock by one millisecond.

Heap statistics
void	k_heap_stats (k_heap_stats_t *stats)
	Capture current heap usage.

Stack statistics
void	k_stack_stats (k_stack_stats_t *stats)
	Measure the main stack's high-water mark.

#define	K_STACK_FILL_WORD 0xA5A5A5A5U
	Word written over the unused main stack at reset.

Detailed Description

Kernel startup, the millisecond uptime clock, and heap usage.

Macro Definition Documentation

◆ K_STACK_FILL_WORD

#define K_STACK_FILL_WORD 0xA5A5A5A5U

Word written over the unused main stack at reset.

The reset handler fills the main-stack reservation below its own frame with this value. k_stack_stats() finds the deepest word that no longer holds it.

Function Documentation

◆ k_init()

void k_init ( void )

Initialize kernel services and the standard streams.

Starts the uptime clock (see k_uptime_init()) and opens /dev/uart0 as descriptors 0, 1, and 2 for stdin, stdout, and stderr. Calls board_panic() if any step fails. main() calls it once, after soc_init() and board_init().

◆ k_uptime_init()

void k_uptime_init ( void )

Start the 1 kHz system timer and register /dev/uptime.

Called by k_init(). Calls board_panic() if the timer cannot produce 1 kHz from board_cpu_clock_hz().

◆ k_uptime_ms()

uint64_t k_uptime_ms ( void )

Read the uptime clock.

Masks interrupts briefly to read the 64-bit counter consistently. Masking interrupts for longer than one tick elsewhere loses time.

Returns: Milliseconds since the system timer started during k_init().

◆ k_tick()

void k_tick ( void )

Advance the uptime clock by one millisecond.

Call only from the 1 kHz system timer interrupt.

◆ k_heap_stats()

void k_heap_stats ( k_heap_stats_t * stats )

Capture current heap usage.

Available memory is reusable + unclaimed, which is not necessarily one contiguous block.

Parameters

[out] stats Destination. Must not be NULL; this is not checked.

◆ k_stack_stats()

void k_stack_stats ( k_stack_stats_t * stats )

Measure the main stack's high-water mark.

Scans the reservation from its lowest address for the first word that was overwritten since reset. used == size means the whole reservation was used and the stack may have overflowed into the heap, which is not detected otherwise. The scan reads up to size bytes; call it from foreground code.