[PATCH] Documentation: kunit: drop obsolete note about uml_abort for coverage

[PATCH] Documentation: kunit: drop obsolete note about uml_abort for coverage

[Daniel Latypov]

Commit b6d5799b0b58 ("kunit: Add 'kunit_shutdown' option") changes KUnit
to call kernel_halt() by default when done testing.

This fixes the issue with not having .gcda files due to not calling
atexit() handlers, and therefore we can stop recommending people
manually tweak UML code.

The need to use older versions of GCC (<=6) remains however, due to
linktime issues, same as before. Note: There also might still be issues
with .gcda files as well in newer versions.

Signed-off-by: Daniel Latypov <dlatypov@google.com>
---
 Documentation/dev-tools/kunit/running_tips.rst | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/Documentation/dev-tools/kunit/running_tips.rst b/Documentation/dev-tools/kunit/running_tips.rst
index 7d99386cf94a..d1626d548fa5 100644
--- a/Documentation/dev-tools/kunit/running_tips.rst
+++ b/Documentation/dev-tools/kunit/running_tips.rst
@@ -86,19 +86,7 @@ Generating code coverage reports under UML
 .. note::
 	TODO(brendanhiggins@google.com): There are various issues with UML and
 	versions of gcc 7 and up. You're likely to run into missing ``.gcda``
-	files or compile errors. We know one `faulty GCC commit
-	<https://github.com/gcc-mirror/gcc/commit/8c9434c2f9358b8b8bad2c1990edf10a21645f9d>`_
-	but not how we'd go about getting this fixed. The compile errors still
-	need some investigation.
-
-.. note::
-	TODO(brendanhiggins@google.com): for recent versions of Linux
-	(5.10-5.12, maybe earlier), there's a bug with gcov counters not being
-	flushed in UML. This translates to very low (<1%) reported coverage. This is
-	related to the above issue and can be worked around by replacing the
-	one call to ``uml_abort()`` (it's in ``os_dump_core()``) with a plain
-	``exit()``.
-
+	files or compile errors.
 
 This is different from the "normal" way of getting coverage information that is
 documented in Documentation/dev-tools/gcov.rst.

base-commit: 87c9c16317882dd6dbbc07e349bc3223e14f3244
-- 
2.32.0.93.g670b81a890-goog

Re: [PATCH] Documentation: kunit: drop obsolete note about uml_abort for coverage

[David Gow]

On Thu, Jun 24, 2021 at 4:17 AM Daniel Latypov <dlatypov@google.com> wrote:
>
> Commit b6d5799b0b58 ("kunit: Add 'kunit_shutdown' option") changes KUnit
> to call kernel_halt() by default when done testing.
>
> This fixes the issue with not having .gcda files due to not calling
> atexit() handlers, and therefore we can stop recommending people
> manually tweak UML code.
>
> The need to use older versions of GCC (<=6) remains however, due to
> linktime issues, same as before. Note: There also might still be issues
> with .gcda files as well in newer versions.
>
> Signed-off-by: Daniel Latypov <dlatypov@google.com>
> ---

This looks good to me, thanks! Now if only we could fix the issues
with newer gcc versions...

Reviewed-by: David Gow <davidgow@google.com>


-- David

>  Documentation/dev-tools/kunit/running_tips.rst | 14 +-------------
>  1 file changed, 1 insertion(+), 13 deletions(-)
>
> diff --git a/Documentation/dev-tools/kunit/running_tips.rst b/Documentation/dev-tools/kunit/running_tips.rst
> index 7d99386cf94a..d1626d548fa5 100644
> --- a/Documentation/dev-tools/kunit/running_tips.rst
> +++ b/Documentation/dev-tools/kunit/running_tips.rst
> @@ -86,19 +86,7 @@ Generating code coverage reports under UML
>  .. note::
>         TODO(brendanhiggins@google.com): There are various issues with UML and
>         versions of gcc 7 and up. You're likely to run into missing ``.gcda``
> -       files or compile errors. We know one `faulty GCC commit
> -       <https://github.com/gcc-mirror/gcc/commit/8c9434c2f9358b8b8bad2c1990edf10a21645f9d>`_
> -       but not how we'd go about getting this fixed. The compile errors still
> -       need some investigation.
> -
> -.. note::
> -       TODO(brendanhiggins@google.com): for recent versions of Linux
> -       (5.10-5.12, maybe earlier), there's a bug with gcov counters not being
> -       flushed in UML. This translates to very low (<1%) reported coverage. This is
> -       related to the above issue and can be worked around by replacing the
> -       one call to ``uml_abort()`` (it's in ``os_dump_core()``) with a plain
> -       ``exit()``.
> -
> +       files or compile errors.
>
>  This is different from the "normal" way of getting coverage information that is
>  documented in Documentation/dev-tools/gcov.rst.
>
> base-commit: 87c9c16317882dd6dbbc07e349bc3223e14f3244
> --
> 2.32.0.93.g670b81a890-goog
>

Re: [PATCH] Documentation: kunit: drop obsolete note about uml_abort for coverage

[Brendan Higgins]

On Wed, Jun 23, 2021 at 1:17 PM Daniel Latypov <dlatypov@google.com> wrote:
>
> Commit b6d5799b0b58 ("kunit: Add 'kunit_shutdown' option") changes KUnit
> to call kernel_halt() by default when done testing.
>
> This fixes the issue with not having .gcda files due to not calling
> atexit() handlers, and therefore we can stop recommending people
> manually tweak UML code.
>
> The need to use older versions of GCC (<=6) remains however, due to
> linktime issues, same as before. Note: There also might still be issues
> with .gcda files as well in newer versions.
>
> Signed-off-by: Daniel Latypov <dlatypov@google.com>

Reviewed-by: Brendan Higgins <brendanhiggins@google.com>