[Intel-gfx] [PATCH i-g-t 3/3] tests: Document ABI extension catchers

[Daniel Vetter]

Our invalid-flags/params testcases are meant to catch abi extensions
by just testing for the next available flag/param. Unfortunately we
need that since without those we forgot to write testcases for these
new flags way too often :(

But it's not entirely clear why this is, so document this trick with
comments.

Also gem_wait wasn't this paranoid, so change the testcase to be so.

Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 tests/gem_ctx_param_basic.c | 3 +++
 tests/gem_exec_params.c     | 3 +++
 tests/gem_wait.c            | 5 ++++-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/tests/gem_ctx_param_basic.c b/tests/gem_ctx_param_basic.c
index 1e7e8ff40703..430a53b22c57 100644
--- a/tests/gem_ctx_param_basic.c
+++ b/tests/gem_ctx_param_basic.c
@@ -149,6 +149,9 @@ igt_main
 		TEST_SUCCESS(LOCAL_IOCTL_I915_GEM_CONTEXT_SETPARAM);
 	}
 
+	/* NOTE: This testcase intentionally tests for the next free parameter
+	 * to catch ABI extensions. Don't "fix" this testcase without adding all
+	 * the tests for the new param first. */
 	ctx_param.param = LOCAL_CONTEXT_PARAM_NO_ZEROMAP + 1;
 
 	igt_subtest("invalid-param-get") {
diff --git a/tests/gem_exec_params.c b/tests/gem_exec_params.c
index e9c13a40f8a7..b33a7408c476 100644
--- a/tests/gem_exec_params.c
+++ b/tests/gem_exec_params.c
@@ -221,6 +221,9 @@ igt_main
 	/* HANDLE_LUT and NO_RELOC are already exercised by gem_exec_lut_handle */
 
 	igt_subtest("invalid-flag") {
+		/* NOTE: This test intentionally exercise the next available
+		 * flag. Don't "fix" this testcase without adding the required
+		 * tests for the new flag first. */
 		execbuf.flags = I915_EXEC_RENDER | (LOCAL_I915_EXEC_RESOURCE_STREAMER << 1);
 		RUN_FAIL(EINVAL);
 	}
diff --git a/tests/gem_wait.c b/tests/gem_wait.c
index 958bf93ff5fd..a785b16e783e 100644
--- a/tests/gem_wait.c
+++ b/tests/gem_wait.c
@@ -236,7 +236,10 @@ static void invalid_flags(int fd)
 
 	wait.bo_handle = handle;
 	wait.timeout_ns = 1;
-	wait.flags = 0xffffffff;
+	/* NOTE: This test intentionally tests for just the next available flag.
+	 * Don't "fix" this testcase without the ABI testcases for new flags
+	 * first. */
+	wait.flags = 1;
 	ret = drmIoctl(fd, DRM_IOCTL_I915_GEM_WAIT, &wait);
 
 	igt_assert(ret != 0 && errno == EINVAL);
-- 
2.5.0