main/gdbserver_tests/README_DEVELOPERS - platform/external/valgrind - Git at Google

 Automatic regression tests:
 ---------------------------
 The Valgrind gdbserver automatic tests are by default
 executed as part of the Valgrind test suite:
    make regtest

 By default, these tests are running with the gdb found at
 Valgrind configure time.

 If you want to test with another gdb version, you can do:
   make regtest GDB=/path/to/another/gdb

 or (to just run the gdbserver tests with another gdb):
   cd gdbserver_tests
   make check
   cd ..
   gdbserver_tests/make_local_links /path/to/another/gdb
   perl tests/vg_regtest gdbserver_tests

 The minimum version to run the tests is gdb >= 6.5.
     Previous versions do not have the 'target remote |' command.  It
     would be possible to use an older version by using the option
     --port of vgdb, and using the tcp/ip variant of the 'target remote'
     GDB command.

 The tests have been run on various platforms using gdb versions >= 7.2
 and on some platforms gdb 7.0 and 7.1.
 Some gdb tests implies a gdb >= 7.2. (these are automatically disabled
 if testing with a lower version).
 Test behaviour with gdb < 7.0 is unknown: some might fail,
 some might block or loop for a very long time.

 Some tests implies to have a vgdb "ptrace invoker" capable.

 The prerequisite are established during make regtest (using marker files).
 Each test verifies the prerequisite using the prereq: line.

 In case of failing tests
 ------------------------
 When executed with a new gdb version and/or depending on the OS version,
 gdbserver tests might often fail due to (irrelevant) differences.
 Such irrelevant differences have to be filtered by gdbserver_tests/filter_gdb.

 You are welcome to fix such bugs by enhancing filter_gdb.

 Alternatively, to report such problems, the best is to re-run
 the gdbserver tests the following way:
    perl tests/vg_regtest --keep-unfiltered gdbserver_tests

 Then file a bug in bugzilla, giving the following information:
   output of
     gdbserver_tests/gdb --version
     uname -a
     cat /etc/issue
     valgrind --version (and/or svn version)
   and attach a tar file containing all the *.out and *.diff
   files in gdbserver_tests directory

 If a gdbserver test fails for other reasons, you can run the test
 manually in two windows:
   In one window, the valgrind
   In another window, you launch gdb yourself, and you copy paste
   the command from xxxx.stdinB.gdb. This might help to see what is
   wrong.

 Another good trick is also to execute the same kind of actions
 using a gdb connected to the gdbserver part of gdb.
 You can examine what is happening by enabling the trace
 of the packets being sent using the gdb command:
    set debug remote 1
 Note however that the packets might be different
 (e.g. the Valgrind gdbserver understands the 'P' packet,
 which might not be understood by the gdbserver of gdb).

 Naming conventions:
 -------------------

 The gdbserver tests are done with various Valgrind tools.  A gdbserver
 test using a tool xxxxxx should have its name starting with the 'short
 two letters code' of this tool.  For example, the test mcvabits.vgtest
 is using Memcheck tool, while the test mssnapshot.vgtest is using
 massif tool.

 Typically, a gdbserver test implies to launch two programs:
      prog: a program running under valgrind
      progB: another program (typically, either gdb or vgdb standalone)
 The conventions about how to specify the 2nd program in a .vgtest
 are explained in the file ../tests/vg_regtest.in
 Many tests are using gdb as progB. The input for gdb is named
 xxxxxx.stdinB.gdb.

 One day, we might imagine to run tests in parallel.
 So, each test gets its own '--vgdb-prefix' argument.
 This also help to avoid interactions between two successive tests:
 if a previous test stayed blocked, the vgdb of the next test
 will not report an error due to multiple possible FIFOs.


 Rational for test approach
 --------------------------
 Two approaches have been looked at:
   V: use the 'vg_regtest' approach used by the rest of Valgrind tests
   G: use the gdb Dejagnu test framework.

 Advantages of V: much simpler that G, known by Valgrind developpers,
 no additional dependency for the Valgrind build and test.

 Disadvantages of V: not well suited to testing of interactive tools,
 very unflexible way to test the results (everything is in "template"
 files), templates contains often irrelevant data for the test but it
 can make the test fail.  After writing 13 tests, it looks like the
 template diff approach is quite fragile (e.g. changing the gdb version
 and/or the OS version influences the output of irrelevant things which
 are part of the template).

 A more flexible template filtering is needed.
 Maybe something like:
 The program under test is outputting its instructions to be filtered in
 special markers e.g.
 #pushf filter_addresses | filter_messages
 ... some output
 #pushf an_additional_filter
 ... some other output, filtered by both the first and second push
 #popf
 ... here output filtered only by the first pushf
 #popf

 Advantages of G: much more powerful, well suited to test a gdb with a
 gdbserver, tests can verify specifically some output without being
 impacted by other output, allow to test Valgrind gdbserver with the
 all of the gdb test suite (but a lot of tests will rather test gdb
 than Valgrind gdbserver).

 Disadvantages: not an easy beast to understand and master, running the
 whole gdb testsuite with Valgrind gdbserver looks to be a challenge.

 Currently, tests are written with vg_regtest. Approach G will be looked at it
 again (e.g. to complement V) once a basic set of tests are available.


 Manual tests still to automate:
 -------------------------------

 Validate  monitor commands abbreviation recognition
 ***************************************************
 mo v.info all_errors            # to show all errors recorded so far
 mo v.i a                        # the same
 mo v                            # must give an error: v can match v.set v.info
 mo v                            # the same            v
 mo v.                           # the same            v.

 test of gdb detaching or dying
 ******************************
 valgrind --vgdb=yes --vgdb-error=0 --vgdb-poll=500 ./t

 in another window

 gdb ./t
 set remotetimeout 100
 target remote|vgdb
 detach                         valgrind continues
 target remote|vgdb             reattach
 detach                         valgrind continues
 target remote|vgdb             reattach
 monitor v.wait                 no effect


 test of valgrind/gdb output redirection
 ***************************************
 valgrind --vgdb=yes --vgdb-error=1 --vgdb-poll=500 ./t

 in another window

 **** command to type***         ****** expected behaviour
 gdb ./t
 set remotetimeout 1000
 target remote | vgdb
 mo v.set vgdb-error 1000        # so that valgrind does stop only at error 1000 and after
 mo v.set gdb_output             # to have further valgrind errors output in gdb
 c                               # continue, some errors will appear
 C-c                             # interrupt program
 mo v.set log_output             # to set back the valgrind output to normal process log output
 mo l                            # leak output to appear in log of process
 mo v.set mixed_output
 mo l                            # leak output to appear in gdb


 test with a big executable: firefox
 ***********************************
 valgrind --vgdb=yes --vgdb-error=1000 --vgdb-poll=50000 --trace-children=yes firefox 2>&1 | tee f.out

 wait for some messages from the "big" firefox executable to appear.
 Then:

 gdb /usr/lib/firefox-3.5/firefox
 target remote | vgdb
 ... then you can do various next/print/bt/bt full/break/... to see it is working

 bulk test with the above
 ************************
 to verify there is no race condition/no reentrance problem
 between gdbserver code and valgrind:
 start firefox like in the previous test.
 In another window, do:
   while true
   do
     vgdb leak
     sleep 1
   done

 NB: this will make firefox run extremely slow, as it will do a leak
 search every second.


 Test of "jump" functionality
 ----------------------------
 ... to be done : put two breaks, jump over one.
 ... same but when error is encountered


 * test with --max-invoke-ms=0
 -----------------------------
 valgrind --vgdb=yes ./t
 ... wait till you see "petachounok sleeping 4 of 15
 then try to gdb it

 !!!! this often causes gdb to report a protocol timeout.
 use gdb set remotetimeout <a big time> to avoid that.
 The symptoms of a timeout are:
     (gdb) tar rem|vgdb --max-invoke-ms=0
     Remote debugging using |vgdb --max-invoke-ms=0
     relaying data between gdb and process 2930
     Ignoring packet error, continuing...
     warning: unrecognized item "timeout" in "qSupported" response

 * tests of shadow registers
 ----------------------------
 Show/modify shadow registers
	Automatic regression tests:
	---------------------------
	The Valgrind gdbserver automatic tests are by default
	executed as part of the Valgrind test suite:
	make regtest

	By default, these tests are running with the gdb found at
	Valgrind configure time.

	If you want to test with another gdb version, you can do:
	make regtest GDB=/path/to/another/gdb

	or (to just run the gdbserver tests with another gdb):
	cd gdbserver_tests
	make check
	cd ..
	gdbserver_tests/make_local_links /path/to/another/gdb
	perl tests/vg_regtest gdbserver_tests

	The minimum version to run the tests is gdb >= 6.5.
	Previous versions do not have the 'target remote \|' command. It
	would be possible to use an older version by using the option
	--port of vgdb, and using the tcp/ip variant of the 'target remote'
	GDB command.

	The tests have been run on various platforms using gdb versions >= 7.2
	and on some platforms gdb 7.0 and 7.1.
	Some gdb tests implies a gdb >= 7.2. (these are automatically disabled
	if testing with a lower version).
	Test behaviour with gdb < 7.0 is unknown: some might fail,
	some might block or loop for a very long time.

	Some tests implies to have a vgdb "ptrace invoker" capable.

	The prerequisite are established during make regtest (using marker files).
	Each test verifies the prerequisite using the prereq: line.

	In case of failing tests
	------------------------
	When executed with a new gdb version and/or depending on the OS version,
	gdbserver tests might often fail due to (irrelevant) differences.
	Such irrelevant differences have to be filtered by gdbserver_tests/filter_gdb.

	You are welcome to fix such bugs by enhancing filter_gdb.

	Alternatively, to report such problems, the best is to re-run
	the gdbserver tests the following way:
	perl tests/vg_regtest --keep-unfiltered gdbserver_tests

	Then file a bug in bugzilla, giving the following information:
	output of
	gdbserver_tests/gdb --version
	uname -a
	cat /etc/issue
	valgrind --version (and/or svn version)
	and attach a tar file containing all the .out and .diff
	files in gdbserver_tests directory

	If a gdbserver test fails for other reasons, you can run the test
	manually in two windows:
	In one window, the valgrind
	In another window, you launch gdb yourself, and you copy paste
	the command from xxxx.stdinB.gdb. This might help to see what is
	wrong.

	Another good trick is also to execute the same kind of actions
	using a gdb connected to the gdbserver part of gdb.
	You can examine what is happening by enabling the trace
	of the packets being sent using the gdb command:
	set debug remote 1
	Note however that the packets might be different
	(e.g. the Valgrind gdbserver understands the 'P' packet,
	which might not be understood by the gdbserver of gdb).

	Naming conventions:
	-------------------

	The gdbserver tests are done with various Valgrind tools. A gdbserver
	test using a tool xxxxxx should have its name starting with the 'short
	two letters code' of this tool. For example, the test mcvabits.vgtest
	is using Memcheck tool, while the test mssnapshot.vgtest is using
	massif tool.

	Typically, a gdbserver test implies to launch two programs:
	prog: a program running under valgrind
	progB: another program (typically, either gdb or vgdb standalone)
	The conventions about how to specify the 2nd program in a .vgtest
	are explained in the file ../tests/vg_regtest.in
	Many tests are using gdb as progB. The input for gdb is named
	xxxxxx.stdinB.gdb.

	One day, we might imagine to run tests in parallel.
	So, each test gets its own '--vgdb-prefix' argument.
	This also help to avoid interactions between two successive tests:
	if a previous test stayed blocked, the vgdb of the next test
	will not report an error due to multiple possible FIFOs.


	Rational for test approach
	--------------------------
	Two approaches have been looked at:
	V: use the 'vg_regtest' approach used by the rest of Valgrind tests
	G: use the gdb Dejagnu test framework.

	Advantages of V: much simpler that G, known by Valgrind developpers,
	no additional dependency for the Valgrind build and test.

	Disadvantages of V: not well suited to testing of interactive tools,
	very unflexible way to test the results (everything is in "template"
	files), templates contains often irrelevant data for the test but it
	can make the test fail. After writing 13 tests, it looks like the
	template diff approach is quite fragile (e.g. changing the gdb version
	and/or the OS version influences the output of irrelevant things which
	are part of the template).

	A more flexible template filtering is needed.
	Maybe something like:
	The program under test is outputting its instructions to be filtered in
	special markers e.g.
	#pushf filter_addresses \| filter_messages
	... some output
	#pushf an_additional_filter
	... some other output, filtered by both the first and second push
	#popf
	... here output filtered only by the first pushf
	#popf

	Advantages of G: much more powerful, well suited to test a gdb with a
	gdbserver, tests can verify specifically some output without being
	impacted by other output, allow to test Valgrind gdbserver with the
	all of the gdb test suite (but a lot of tests will rather test gdb
	than Valgrind gdbserver).

	Disadvantages: not an easy beast to understand and master, running the
	whole gdb testsuite with Valgrind gdbserver looks to be a challenge.

	Currently, tests are written with vg_regtest. Approach G will be looked at it
	again (e.g. to complement V) once a basic set of tests are available.


	Manual tests still to automate:
	-------------------------------

	Validate monitor commands abbreviation recognition
	***************************************************
	mo v.info all_errors # to show all errors recorded so far
	mo v.i a # the same
	mo v # must give an error: v can match v.set v.info
	mo v # the same v
	mo v. # the same v.

	test of gdb detaching or dying
	******************************
	valgrind --vgdb=yes --vgdb-error=0 --vgdb-poll=500 ./t

	in another window

	gdb ./t
	set remotetimeout 100
	target remote\|vgdb
	detach valgrind continues
	target remote\|vgdb reattach
	detach valgrind continues
	target remote\|vgdb reattach
	monitor v.wait no effect



	test of valgrind/gdb output redirection
	***************************************
	valgrind --vgdb=yes --vgdb-error=1 --vgdb-poll=500 ./t

	in another window

	** command to type* ****** expected behaviour
	gdb ./t
	set remotetimeout 1000
	target remote \| vgdb
	mo v.set vgdb-error 1000 # so that valgrind does stop only at error 1000 and after
	mo v.set gdb_output # to have further valgrind errors output in gdb
	c # continue, some errors will appear
	C-c # interrupt program
	mo v.set log_output # to set back the valgrind output to normal process log output
	mo l # leak output to appear in log of process
	mo v.set mixed_output
	mo l # leak output to appear in gdb



	test with a big executable: firefox
	***********************************
	valgrind --vgdb=yes --vgdb-error=1000 --vgdb-poll=50000 --trace-children=yes firefox 2>&1 \| tee f.out

	wait for some messages from the "big" firefox executable to appear.
	Then:

	gdb /usr/lib/firefox-3.5/firefox
	target remote \| vgdb
	... then you can do various next/print/bt/bt full/break/... to see it is working

	bulk test with the above
	************************
	to verify there is no race condition/no reentrance problem
	between gdbserver code and valgrind:
	start firefox like in the previous test.
	In another window, do:
	while true
	do
	vgdb leak
	sleep 1
	done

	NB: this will make firefox run extremely slow, as it will do a leak
	search every second.


	Test of "jump" functionality
	----------------------------
	... to be done : put two breaks, jump over one.
	... same but when error is encountered


	* test with --max-invoke-ms=0
	-----------------------------
	valgrind --vgdb=yes ./t
	... wait till you see "petachounok sleeping 4 of 15
	then try to gdb it

	!!!! this often causes gdb to report a protocol timeout.
	use gdb set remotetimeout <a big time> to avoid that.
	The symptoms of a timeout are:
	(gdb) tar rem\|vgdb --max-invoke-ms=0
	Remote debugging using \|vgdb --max-invoke-ms=0
	relaying data between gdb and process 2930
	Ignoring packet error, continuing...
	warning: unrecognized item "timeout" in "qSupported" response

	* tests of shadow registers
	----------------------------
	Show/modify shadow registers