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STACK(9)	       FreeBSD Kernel Developer's Manual	      STACK(9)

NAME
     stack -- kernel thread stack tracing routines

SYNOPSIS
     #include <sys/param.h>
     #include <sys/stack.h>
     In	the kernel configuration file:
     options DDB
     options STACK

     struct stack *
     stack_create(void);

     void
     stack_destroy(struct stack	*st);

     int
     stack_put(struct stack *st, vm_offset_t pc);

     void
     stack_copy(struct stack *src, struct stack	dst);

     void
     stack_zero(struct stack *st);

     void
     stack_print(struct	stack *st);

     void
     stack_print_ddb(struct stack *st);

     void
     stack_print_short(struct stack *st);

     void
     stack_print_short_ddb(struct stack	*st);

     void
     stack_sbuf_print(struct sbuf sb*, struct stack *st);

     void
     stack_sbuf_print_ddb(struct sbuf sb*, struct stack	*st);

     void
     stack_save(struct stack *st);

DESCRIPTION
     The stack KPI allows querying of kernel stack trace information and the
     automated generation of kernel stack trace	strings	for the	purposes of
     debugging and tracing.  To	use the	KPI, at	least one of options DDB and
     options STACK must	be compiled into the kernel.

     Each stack	trace is described by a	struct stack.  Before a	trace may be
     created or	otherwise manipulated, storage for the trace must be allocated
     with stack_create(), which	may sleep.  Memory associated with a trace is
     freed by calling stack_destroy().

     A trace of	the current kernel thread's call stack may be captured using
     stack_save().

     stack_print() and stack_print_short() may be used to print	a stack	trace
     using the kernel printf(9), and may sleep as a result of acquiring	sx(9)
     locks in the kernel linker	while looking up symbol	names.	In locking-
     sensitive environments, the unsynchronized	stack_print_ddb() and
     stack_print_short_ddb() variants may be invoked.  This function bypasses
     kernel linker locking, making it usable in	ddb(4),	but not	in a live sys-
     tem where linker data structures may change.

     stack_sbuf_print()	may be used to construct a human-readable string,
     including conversion (where possible) from	a simple kernel	instruction
     pointer to	a named	symbol and offset.  The	argument sb must be an ini-
     tialized struct sbuf as described in sbuf(9).  This function may sleep if
     an	auto-extending struct sbuf is used, or due to kernel linker locking.
     In	locking-sensitive environments,	such as	ddb(4),	the unsynchronized
     stack_sbuf_print_ddb() variant may	be invoked to avoid kernel linker
     locking; it should	be used	with a fixed-length sbuf.

     The utility functions stack_zero, stack_copy, and stack_put may be	used
     to	manipulate stack data structures directly.

SEE ALSO
     ddb(4), printf(9),	sbuf(9), sx(9)

AUTHORS
     The stack(9) function suite was created by	Antoine	Brodin.	 stack(9) was
     extended by Robert	Watson for general-purpose use outside of ddb(4).

FreeBSD	11.1			 June 24, 2009			  FreeBSD 11.1
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | AUTHORS

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