[lttng-modules.git] / tools / syscalls / README

LTTng system call tracing

1) lttng-syscall-extractor

You need to build a kernel with CONFIG_FTRACE_SYSCALLS=y and
CONFIG_KALLSYMS_ALL=y for extraction. Apply the linker patch to get your
kernel to keep the system call metadata after boot.  Then build and load
the LTTng syscall extractor module. The module will fail to load (this
is expected). See the dmesg output for system call metadata.

2) Generate system call TRACE_EVENT().

Take the dmesg data and feed it to lttng-syscalls-generate-headers.sh from the
tools/syscalls directory. See the script header for usage example. It should be
run for both the integers and pointers types.

After these are created, you just need to follow the new system call additions,
no need to regenerate the whole thing, since system calls are only appended to.

3) Override headers

You need to provide override headers (even if they don't contain
overrides) for each architecture. Those are meant to contain manual
overrides for specific system calls for cases where the script do not
generate the correct typing for specific system calls.

4) Integrating the new architecture, updating architecture header

Edit instrumentation/syscalls/syscalls_integers.h and
instrumentation/syscalls/syscalls_pointers.h. Add the new architecture (e.g.
CONFIG_X86_64) to the newly-generated headers (e.g. changing the current
x86-64-syscalls_<CLASS>.h into x86-64-syscalls_<CLASS>.h), then rebuild
lttng-modules.
Commit	Line	Data
	1	LTTng system call tracing
	2
	3	1) lttng-syscall-extractor
	4
	5	You need to build a kernel with CONFIG_FTRACE_SYSCALLS=y and
	6	CONFIG_KALLSYMS_ALL=y for extraction. Apply the linker patch to get your
	7	kernel to keep the system call metadata after boot. Then build and load
	8	the LTTng syscall extractor module. The module will fail to load (this
	9	is expected). See the dmesg output for system call metadata.
	10
	11	2) Generate system call TRACE_EVENT().
	12
	13	Take the dmesg data and feed it to lttng-syscalls-generate-headers.sh from the
	14	tools/syscalls directory. See the script header for usage example. It should be
	15	run for both the integers and pointers types.
	16
	17	After these are created, you just need to follow the new system call additions,
	18	no need to regenerate the whole thing, since system calls are only appended to.
	19
	20	3) Override headers
	21
	22	You need to provide override headers (even if they don't contain
	23	overrides) for each architecture. Those are meant to contain manual
	24	overrides for specific system calls for cases where the script do not
	25	generate the correct typing for specific system calls.
	26
	27	4) Integrating the new architecture, updating architecture header
	28
	29	Edit instrumentation/syscalls/syscalls_integers.h and
	30	instrumentation/syscalls/syscalls_pointers.h. Add the new architecture (e.g.
	31	CONFIG_X86_64) to the newly-generated headers (e.g. changing the current
	32	x86-64-syscalls_<CLASS>.h into x86-64-syscalls_<CLASS>.h), then rebuild
	33	lttng-modules.