[lttng-modules.git] / instrumentation / 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 metadata and feed it to lttng-syscalls-generate-headers.sh
(do not include the ending SUCCESS line), e.g., from the
instrumentation/syscalls directory. See the script header for usage example.
It should be run for both the integers and pointers types.

After these are created, we 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/headers/syscalls_integers.h and
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-3.10.0-rc7_<CLASS>.h into
x86-64-syscalls-3.13.7_<CLASS>.h), then rebuild lttng-modules.
Commit	Line	Data
5fee13fd MD	1	LTTng system call tracing
	2
	3	1) lttng-syscall-extractor
	4
deeaaf53 MD	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.
5fee13fd MD	10
	11	2) Generate system call TRACE_EVENT().
	12
94f9e233 MD	13	Take the dmesg metadata and feed it to lttng-syscalls-generate-headers.sh
	14	(do not include the ending SUCCESS line), e.g., from the
	15	instrumentation/syscalls directory. See the script header for usage example.
	16	It should be run for both the integers and pointers types.
5fee13fd MD	17
	18	After these are created, we just need to follow the new system call additions,
	19	no need to regenerate the whole thing, since system calls are only appended to.
94f9e233 MD	20
	21	3) Override headers
	22
	23	You need to provide override headers (even if they don't contain
	24	overrides) for each architecture. Those are meant to contain manual
	25	overrides for specific system calls for cases where the script do not
	26	generate the correct typing for specific system calls.
	27
	28	4) Integrating the new architecture, updating architecture header
	29
	30	Edit instrumentation/syscalls/headers/syscalls_integers.h and
	31	syscalls_pointers.h. Add the new architecture
	32	(e.g. CONFIG_X86_64) to the newly-generated headers
	33	(e.g. changing the current x86-64-syscalls-3.10.0-rc7_<CLASS>.h into
	34	x86-64-syscalls-3.13.7_<CLASS>.h), then rebuild lttng-modules.