linux-kernel - Re: [PATCH] Documentation: kunit: drop obsolete note about uml

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Date:   Fri, 25 Jun 2021 12:08:02 +0800
From:   David Gow <davidgow@...gle.com>
To:     Daniel Latypov <dlatypov@...gle.com>
Cc:     Brendan Higgins <brendanhiggins@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        KUnit Development <kunit-dev@...glegroups.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] Documentation: kunit: drop obsolete note about uml_abort
 for coverage

On Thu, Jun 24, 2021 at 4:17 AM Daniel Latypov <dlatypov@...gle.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@...gle.com>
> ---

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

Reviewed-by: David Gow <davidgow@...gle.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@...gle.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@...gle.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
>