u-boot-brain/test
Stephen Warren 89ab841088 test/py: support running sandbox under gdbserver
Implement command--line option --gdbserver COMM, which does two things:

a) Run the sandbox process under gdbserver, using COMM as gdbserver's
   communication channel.

b) Disables all timeouts, so that if U-Boot is halted under the debugger,
   tests don't fail. If the user gives up in the middle of a debugging
   session, they can simply CTRL-C the test script to abort it.

This allows easy debugging of test failures without having to manually
re-create the failure conditions. Usage is:

Window 1:
./test/py/test.py --bd sandbox --gdbserver localhost:1234

Window 2:
gdb ./build-sandbox/u-boot -ex 'target remote localhost:1234'

When using this option, it likely makes sense to use pytest's -k option
to limit the set of tests that are executed.

Simply running U-Boot directly under gdb (rather than gdbserver) was
also considered. However, this was rejected because:

a) gdb's output would then be processed by the test script, and likely
   confuse it causing false failures.

b) pytest by default hides stdout from tests, which would prevent the
   user from interacting with gdb.

   While gdb can be told to redirect the debugee's stdio to a separate
   PTY, this would appear to leave gdb's stdio directed at the test
   scripts and the debugee's stdio directed elsewhere, which is the
   opposite of the desired effect. Perhaps some complicated PTY muxing
   and process hierarchy could invert this. However, the current scheme
   is simple to implement and use, so it doesn't seem worth complicating
   matters.

c) Using gdbserver allows arbitrary debuggers to be used, even those with
   a GUI. If the test scripts invoked the debugger themselves, they'd have
   to know how to execute arbitary applications. While the user could hide
   this all in a wrapper script, this feels like extra complication.

An interesting future idea might be a --gdb-screen option, which could
spawn both U-Boot and gdb separately, and spawn the screen into a newly
created window under screen. Similar options could be envisaged for
creating a new xterm/... too.

--gdbserver  currently only supports sandbox, and not real hardware.
That's primarily because the test hooks are responsible for all aspects of
hardware control, so there's nothing for the test scripts themselves can
do to enable gdbserver on real hardware. We might consider introducing a
separate --disable-timeouts option to support use of debuggers on real
hardware, and having --gdbserver imply that option.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
2016-02-08 10:22:39 -05:00
..
dm video: test: Adjust order of file closure 2016-02-06 13:57:15 +01:00
env test: env: Add a test of the new regex behavior for attrs 2015-05-21 09:16:18 -04:00
fs test/fs: error case fixes/enhancements 2016-01-13 21:05:21 -05:00
image add test for two 'loadables' 2015-05-28 08:18:21 -04:00
py test/py: support running sandbox under gdbserver 2016-02-08 10:22:39 -05:00
stdint test: Add a simple test to detected warnings with uint64_t, uintptr_t 2014-10-27 11:04:01 -04:00
trace test: Add a test for command repeat 2014-09-24 18:30:28 -04:00
vboot Implement generalised RSA public exponents for verified boot 2014-08-09 11:17:01 -04:00
cmd_ut.c test: env: Add test framework for env 2015-05-21 09:16:18 -04:00
command_ut.c test/py: test the shell if command 2016-01-20 19:06:23 -07:00
common.sh test: Add a test for command repeat 2014-09-24 18:30:28 -04:00
compression.c Add support for LZ4 decompression algorithm 2015-10-11 17:12:10 -04:00
Kconfig test: env: Add test framework for env 2015-05-21 09:16:18 -04:00
Makefile test: dm: Move the time test over to the ut command 2015-05-21 09:16:17 -04:00
time_ut.c test: dm: Move the time test over to the ut command 2015-05-21 09:16:17 -04:00
ut.c test: Record and silence console in tests 2015-11-19 20:27:51 -07:00