[PATCH 0/4] kernel-doc: fix -Werror issues

[PATCH 0/4] kernel-doc: fix -Werror issues

[Mauro Carvalho Chehab]

Hi Jon,

As pointed by Jani, and previously by Randy, several warnings
are currently not considered as errors. The issue is related
to changeset 469c1c9eb6c9 ("kernel-doc: Issue warnings that were silently
discarded"), which was using directly a low-level interface.

Patch 1 fix that.
Patch 2 fixes a related issue: when there are more than 255
errors, the return code with -Werror can be 0 even on errors,
because of glibc behavior: programs can only use 8 bits for
error codes.

Patches 3 and 4 are not directly related, and touches only
on comments inside python-doc.py script itself:

- patch 3 is just a coding style change to match the comment
  style we agreed;

- patch 4 fixes some English issues on comments. The issues
  were pointed by LLM, which was used as any other spelling
  tool: I picked just the relevant changes, ignoring the ones
  that were false positives. I also didn't agree with one of
  the changes, replacing it by something else.

  I wrote it more as an experiment about how to properly use
  LLM. IMO, it could be useful to use LLM to review spelling
  on docs, provided that the one using the tool will filter
  out LLM-generated trash - just like one does when using any
  other spelling tool.

Mauro Carvalho Chehab (4):
  scripts/kernel-doc: fix logic to handle unissued warnings
  scripts/kernel-doc: avoid error_count overflows
  scripts/kernel-doc: ensure that comments are using our coding style
  scripts/kernel-doc: some fixes to kernel-doc comments

 scripts/kernel-doc.py                | 72 +++++++++++++++++++---------
 tools/lib/python/kdoc/kdoc_parser.py |  6 ++-
 2 files changed, 55 insertions(+), 23 deletions(-)

-- 
2.52.0

[PATCH 1/4] scripts/kernel-doc: fix logic to handle unissued warnings

[Mauro Carvalho Chehab]

Changeset 469c1c9eb6c9 ("kernel-doc: Issue warnings that were silently discarded")
didn't properly addressed the missing messages behavior, as
it was calling directly python logger low-level function,
instead of using the expected method to emit warnings.

Basically, there are two methods to log messages:

- self.config.log.warning() - This is the raw level to emit a
  warning. It just writes the a message at stderr, via python
  logging, as it is initialized as:

    self.config.log = logging.getLogger("kernel-doc")

- self.config.warning() - This is where we actually consider a
  message as a warning, properly incrementing error count.

Due to that, several parsing error messages are internally considered
as success, causing -Werror to not work on such messages.

While here, ensure that the last ignored entry will also be handled
by adding an extra check at the end of the parse handler.

Fixes: 469c1c9eb6c9 ("kernel-doc: Issue warnings that were silently discarded")
Closes: https://lore.kernel.org/linux-doc/20260112091053.00cee29a@foz.lan/
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 tools/lib/python/kdoc/kdoc_parser.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/lib/python/kdoc/kdoc_parser.py b/tools/lib/python/kdoc/kdoc_parser.py
index a9a37519145d..aed07fdaa561 100644
--- a/tools/lib/python/kdoc/kdoc_parser.py
+++ b/tools/lib/python/kdoc/kdoc_parser.py
@@ -459,7 +459,7 @@ class KernelDoc:
         #
         if self.entry and self.entry not in self.entries:
             for log_msg in self.entry.warnings:
-                self.config.log.warning(log_msg)
+                self.config.warning(log_msg)
 
         self.entry = KernelEntry(self.config, self.fname, ln)
 
@@ -1741,6 +1741,10 @@ class KernelDoc:
                         # Hand this line to the appropriate state handler
                         self.state_actions[self.state](self, ln, line)
 
+            if self.entry and self.entry not in self.entries:
+                for log_msg in self.entry.warnings:
+                    self.config.warning(log_msg)
+
         except OSError:
             self.config.log.error(f"Error: Cannot open file {self.fname}")
 
-- 
2.52.0

[PATCH 2/4] scripts/kernel-doc: avoid error_count overflows

[Mauro Carvalho Chehab]

The glibc library limits the return code to 8 bits. We need to
stick to this limit when using sys.exit(error_count).

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 scripts/kernel-doc.py | 32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/scripts/kernel-doc.py b/scripts/kernel-doc.py
index 7a1eaf986bcd..600bdfea6a96 100755
--- a/scripts/kernel-doc.py
+++ b/scripts/kernel-doc.py
@@ -176,7 +176,14 @@ class MsgFormatter(logging.Formatter):
         return logging.Formatter.format(self, record)
 
 def main():
-    """Main program"""
+    """
+    Main program
+    By default, the return value is zero on parsing errors or when the
+    Python version is not compatible with kernel-doc. The rationale is
+    to not break Linux compilation on such cases.
+    If -Werror is used, it will return the number of parse errors, up to
+    255 errors, as this is the maximum value allowed by glibc.
+    """
 
     parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter,
                                      description=DESC)
@@ -321,18 +328,23 @@ def main():
     if not error_count:
         sys.exit(0)
 
+    if args.verbose:
+        print("%s errors" % error_count)                # pylint: disable=C0209
+
+
     if args.werror:
         print("%s warnings as errors" % error_count)    # pylint: disable=C0209
+
+        #
+        # Return code is 8-bits, as seen at:
+        #   https://www.gnu.org/software/libc/manual/html_node/Exit-Status.html
+        # Truncate to avoid overflow
+        #
+        if error_count > 255:
+            error_count = 255
+
         sys.exit(error_count)
-
-    if args.verbose:
-        print("%s errors" % error_count)                # pylint: disable=C0209
-
-    if args.none:
-        sys.exit(0)
-
-    sys.exit(error_count)
-
+    sys.exit(0)
 
 # Call main method
 if __name__ == "__main__":
-- 
2.52.0

[PATCH 3/4] scripts/kernel-doc: ensure that comments are using our coding style

[Mauro Carvalho Chehab]

Along kernel-doc libs, we opted to have all comments starting/ending
with a blank comment line. Use the same style here.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 scripts/kernel-doc.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/scripts/kernel-doc.py b/scripts/kernel-doc.py
index 600bdfea6a96..bcb60136fc9c 100755
--- a/scripts/kernel-doc.py
+++ b/scripts/kernel-doc.py
@@ -188,7 +188,9 @@ def main():
     parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter,
                                      description=DESC)
 
+    #
     # Normal arguments
+    #
 
     parser.add_argument("-v", "-verbose", "--verbose", action="store_true",
                         help="Verbose output, more warnings and other information.")
@@ -204,7 +206,9 @@ def main():
                         action="store_true",
                         help="Enable line number output (only in ReST mode)")
 
+    #
     # Arguments to control the warning behavior
+    #
 
     parser.add_argument("-Wreturn", "--wreturn", action="store_true",
                         help="Warns about the lack of a return markup on functions.")
@@ -226,7 +230,9 @@ def main():
     parser.add_argument("-export-file", "--export-file", action='append',
                         help=EXPORT_FILE_DESC)
 
+    #
     # Output format mutually-exclusive group
+    #
 
     out_group = parser.add_argument_group("Output format selection (mutually exclusive)")
 
@@ -239,7 +245,9 @@ def main():
     out_fmt.add_argument("-N", "-none", "--none", action="store_true",
                          help="Do not output documentation, only warnings.")
 
+    #
     # Output selection mutually-exclusive group
+    #
 
     sel_group = parser.add_argument_group("Output selection (mutually exclusive)")
     sel_mut = sel_group.add_mutually_exclusive_group()
@@ -253,7 +261,9 @@ def main():
     sel_mut.add_argument("-s", "-function", "--symbol", action='append',
                          help=FUNCTION_DESC)
 
+    #
     # Those are valid for all 3 types of filter
+    #
     parser.add_argument("-n", "-nosymbol", "--nosymbol", action='append',
                         help=NOSYMBOL_DESC)
 
@@ -286,9 +296,11 @@ def main():
 
     python_ver = sys.version_info[:2]
     if python_ver < (3,6):
+        #
         # Depending on Kernel configuration, kernel-doc --none is called at
         # build time. As we don't want to break compilation due to the
         # usage of an old Python version, return 0 here.
+        #
         if args.none:
             logger.error("Python 3.6 or later is required by kernel-doc. skipping checks")
             sys.exit(0)
@@ -298,7 +310,9 @@ def main():
     if python_ver < (3,7):
         logger.warning("Python 3.7 or later is required for correct results")
 
+    #
     # Import kernel-doc libraries only after checking Python version
+    #
     from kdoc.kdoc_files import KernelFiles             # pylint: disable=C0415
     from kdoc.kdoc_output import RestFormat, ManFormat  # pylint: disable=C0415
 
@@ -346,6 +360,8 @@ def main():
         sys.exit(error_count)
     sys.exit(0)
 
+#
 # Call main method
+#
 if __name__ == "__main__":
     main()
-- 
2.52.0

[PATCH 4/4] scripts/kernel-doc: some fixes to kernel-doc comments

[Mauro Carvalho Chehab]

There are some typos and English errors at the kernel-doc.py comments.

Locate them with the help of LLM (gpt-oss 14B), locally excecuted
with this prompt:

    review English grammar andsyntax at the comments on the code
    below:
    <cat scripts/kernel-doc.py>

Not all results are flowers, although it caught several minor
issues there. Add the pertinent fixes, discarding the bad ones.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 scripts/kernel-doc.py | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/scripts/kernel-doc.py b/scripts/kernel-doc.py
index bcb60136fc9c..5086248ee532 100755
--- a/scripts/kernel-doc.py
+++ b/scripts/kernel-doc.py
@@ -9,10 +9,10 @@
 #       The rationale is that it shall fail gracefully during Kernel
 #       compilation with older Kernel versions. Due to that:
 #       - encoding line is needed here;
-#       - no f-strings can be used on this file.
-#       - the libraries that require newer versions can only be included
-#         after Python version is checked.
-
+#       - f‑strings cannot be used in this file.
+#       - libraries that require newer versions can only be included
+#         after the Python version has been checked.
+#
 # Converted from the kernel-doc script originally written in Perl
 # under GPLv2, copyrighted since 1998 by the following authors:
 #
@@ -132,13 +132,13 @@ May be used multiple times.
 """
 
 EXPORT_DESC = """
-Only output documentation for the symbols that have been
+Only output documentation for symbols that have been
 exported using EXPORT_SYMBOL() and related macros in any input
 FILE or -export-file FILE.
 """
 
 INTERNAL_DESC = """
-Only output documentation for the symbols that have NOT been
+Only output documentation for symbols that have NOT been
 exported using EXPORT_SYMBOL() and related macros in any input
 FILE or -export-file FILE.
 """
@@ -161,7 +161,7 @@ Header and C source files to be parsed.
 """
 
 WARN_CONTENTS_BEFORE_SECTIONS_DESC = """
-Warns if there are contents before sections (deprecated).
+Warn if there are contents before sections (deprecated).
 
 This option is kept just for backward-compatibility, but it does nothing,
 neither here nor at the original Perl script.
@@ -169,7 +169,7 @@ neither here nor at the original Perl script.
 
 
 class MsgFormatter(logging.Formatter):
-    """Helper class to format warnings on a similar way to kernel-doc.pl"""
+    """Helper class to format warnings in a similar way to kernel-doc.pl."""
 
     def format(self, record):
         record.levelname = record.levelname.capitalize()
@@ -268,7 +268,7 @@ def main():
                         help=NOSYMBOL_DESC)
 
     parser.add_argument("-D", "-no-doc-sections", "--no-doc-sections",
-                        action='store_true', help="Don't outputt DOC sections")
+                        action='store_true', help="Don't output DOC sections")
 
     parser.add_argument("files", metavar="FILE",
                         nargs="+", help=FILES_DESC)
@@ -297,12 +297,12 @@ def main():
     python_ver = sys.version_info[:2]
     if python_ver < (3,6):
         #
-        # Depending on Kernel configuration, kernel-doc --none is called at
+        # Depending on the Kernel configuration, kernel-doc --none is called at
         # build time. As we don't want to break compilation due to the
         # usage of an old Python version, return 0 here.
         #
         if args.none:
-            logger.error("Python 3.6 or later is required by kernel-doc. skipping checks")
+            logger.error("Python 3.6 or later is required by kernel‑doc. Skipping checks")
             sys.exit(0)
 
         sys.exit("Python 3.6 or later is required by kernel-doc. Aborting.")
@@ -311,7 +311,7 @@ def main():
         logger.warning("Python 3.7 or later is required for correct results")
 
     #
-    # Import kernel-doc libraries only after checking Python version
+    # Import kernel-doc libraries only after checking the Python version
     #
     from kdoc.kdoc_files import KernelFiles             # pylint: disable=C0415
     from kdoc.kdoc_output import RestFormat, ManFormat  # pylint: disable=C0415
-- 
2.52.0

Re: [PATCH 1/4] scripts/kernel-doc: fix logic to handle unissued warnings

[Andy Shevchenko]

On Mon, Jan 12, 2026 at 12:23:23PM +0100, Mauro Carvalho Chehab wrote:
> Changeset 469c1c9eb6c9 ("kernel-doc: Issue warnings that were silently discarded")
> didn't properly addressed the missing messages behavior, as
> it was calling directly python logger low-level function,
> instead of using the expected method to emit warnings.
> 
> Basically, there are two methods to log messages:
> 
> - self.config.log.warning() - This is the raw level to emit a
>   warning. It just writes the a message at stderr, via python
>   logging, as it is initialized as:
> 
>     self.config.log = logging.getLogger("kernel-doc")
> 
> - self.config.warning() - This is where we actually consider a
>   message as a warning, properly incrementing error count.
> 
> Due to that, several parsing error messages are internally considered
> as success, causing -Werror to not work on such messages.
> 
> While here, ensure that the last ignored entry will also be handled
> by adding an extra check at the end of the parse handler.

Thanks for addressing these issues, Mauro!

I am not promising I will test this soon, but from code perspective it looks
good to me,
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 2/4] scripts/kernel-doc: avoid error_count overflows

[Jani Nikula]

On Mon, 12 Jan 2026, Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:
> The glibc library limits the return code to 8 bits. We need to
> stick to this limit when using sys.exit(error_count).
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> ---
>  scripts/kernel-doc.py | 32 ++++++++++++++++++++++----------
>  1 file changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/scripts/kernel-doc.py b/scripts/kernel-doc.py
> index 7a1eaf986bcd..600bdfea6a96 100755
> --- a/scripts/kernel-doc.py
> +++ b/scripts/kernel-doc.py
> @@ -176,7 +176,14 @@ class MsgFormatter(logging.Formatter):
>          return logging.Formatter.format(self, record)
>  
>  def main():
> -    """Main program"""
> +    """
> +    Main program
> +    By default, the return value is zero on parsing errors or when the
> +    Python version is not compatible with kernel-doc. The rationale is
> +    to not break Linux compilation on such cases.
> +    If -Werror is used, it will return the number of parse errors, up to
> +    255 errors, as this is the maximum value allowed by glibc.
> +    """
>  
>      parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter,
>                                       description=DESC)
> @@ -321,18 +328,23 @@ def main():
>      if not error_count:
>          sys.exit(0)
>  
> +    if args.verbose:
> +        print("%s errors" % error_count)                # pylint: disable=C0209
> +
> +
>      if args.werror:
>          print("%s warnings as errors" % error_count)    # pylint: disable=C0209
> +
> +        #
> +        # Return code is 8-bits, as seen at:
> +        #   https://www.gnu.org/software/libc/manual/html_node/Exit-Status.html
> +        # Truncate to avoid overflow
> +        #
> +        if error_count > 255:
> +            error_count = 255

What's the point in returning the error count anyway?

I'd rather see some error/warning classification in the exit code than a
count. Like, the argparser uses exit code 2 by default, so you can't
even trust the exit code to return the count anyway.

BR,
Jani.

> +
>          sys.exit(error_count)
> -
> -    if args.verbose:
> -        print("%s errors" % error_count)                # pylint: disable=C0209
> -
> -    if args.none:
> -        sys.exit(0)
> -
> -    sys.exit(error_count)
> -
> +    sys.exit(0)
>  
>  # Call main method
>  if __name__ == "__main__":

-- 
Jani Nikula, Intel

Re: [PATCH 4/4] scripts/kernel-doc: some fixes to kernel-doc comments

[Jani Nikula]

On Mon, 12 Jan 2026, Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:
> There are some typos and English errors at the kernel-doc.py comments.
>
> Locate them with the help of LLM (gpt-oss 14B), locally excecuted
> with this prompt:
>
>     review English grammar andsyntax at the comments on the code
>     below:
>     <cat scripts/kernel-doc.py>
>
> Not all results are flowers, although it caught several minor
> issues there. Add the pertinent fixes, discarding the bad ones.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> ---
>  scripts/kernel-doc.py | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/scripts/kernel-doc.py b/scripts/kernel-doc.py
> index bcb60136fc9c..5086248ee532 100755
> --- a/scripts/kernel-doc.py
> +++ b/scripts/kernel-doc.py
> @@ -9,10 +9,10 @@
>  #       The rationale is that it shall fail gracefully during Kernel
>  #       compilation with older Kernel versions. Due to that:
>  #       - encoding line is needed here;
> -#       - no f-strings can be used on this file.
> -#       - the libraries that require newer versions can only be included
> -#         after Python version is checked.
> -
> +#       - f‑strings cannot be used in this file.
> +#       - libraries that require newer versions can only be included
> +#         after the Python version has been checked.
> +#
>  # Converted from the kernel-doc script originally written in Perl
>  # under GPLv2, copyrighted since 1998 by the following authors:
>  #
> @@ -132,13 +132,13 @@ May be used multiple times.
>  """
>  
>  EXPORT_DESC = """
> -Only output documentation for the symbols that have been
> +Only output documentation for symbols that have been
>  exported using EXPORT_SYMBOL() and related macros in any input
>  FILE or -export-file FILE.
>  """
>  
>  INTERNAL_DESC = """
> -Only output documentation for the symbols that have NOT been
> +Only output documentation for symbols that have NOT been
>  exported using EXPORT_SYMBOL() and related macros in any input
>  FILE or -export-file FILE.
>  """
> @@ -161,7 +161,7 @@ Header and C source files to be parsed.
>  """
>  
>  WARN_CONTENTS_BEFORE_SECTIONS_DESC = """
> -Warns if there are contents before sections (deprecated).
> +Warn if there are contents before sections (deprecated).
>  
>  This option is kept just for backward-compatibility, but it does nothing,
>  neither here nor at the original Perl script.
> @@ -169,7 +169,7 @@ neither here nor at the original Perl script.
>  
>  
>  class MsgFormatter(logging.Formatter):
> -    """Helper class to format warnings on a similar way to kernel-doc.pl"""
> +    """Helper class to format warnings in a similar way to kernel-doc.pl."""
>  
>      def format(self, record):
>          record.levelname = record.levelname.capitalize()
> @@ -268,7 +268,7 @@ def main():
>                          help=NOSYMBOL_DESC)
>  
>      parser.add_argument("-D", "-no-doc-sections", "--no-doc-sections",
> -                        action='store_true', help="Don't outputt DOC sections")
> +                        action='store_true', help="Don't output DOC sections")
>  
>      parser.add_argument("files", metavar="FILE",
>                          nargs="+", help=FILES_DESC)
> @@ -297,12 +297,12 @@ def main():
>      python_ver = sys.version_info[:2]
>      if python_ver < (3,6):
>          #
> -        # Depending on Kernel configuration, kernel-doc --none is called at
> +        # Depending on the Kernel configuration, kernel-doc --none is called at
>          # build time. As we don't want to break compilation due to the
>          # usage of an old Python version, return 0 here.
>          #
>          if args.none:
> -            logger.error("Python 3.6 or later is required by kernel-doc. skipping checks")
> +            logger.error("Python 3.6 or later is required by kernel‑doc. Skipping checks")

Please don't add silly non-breaking space in there.

>              sys.exit(0)
>  
>          sys.exit("Python 3.6 or later is required by kernel-doc. Aborting.")
> @@ -311,7 +311,7 @@ def main():
>          logger.warning("Python 3.7 or later is required for correct results")
>  
>      #
> -    # Import kernel-doc libraries only after checking Python version
> +    # Import kernel-doc libraries only after checking the Python version
>      #
>      from kdoc.kdoc_files import KernelFiles             # pylint: disable=C0415
>      from kdoc.kdoc_output import RestFormat, ManFormat  # pylint: disable=C0415

-- 
Jani Nikula, Intel

Re: [PATCH 2/4] scripts/kernel-doc: avoid error_count overflows

[Mauro Carvalho Chehab]

On Mon, Jan 12, 2026 at 02:02:10PM +0200, Jani Nikula wrote:
> On Mon, 12 Jan 2026, Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:
> > The glibc library limits the return code to 8 bits. We need to
> > stick to this limit when using sys.exit(error_count).
> >
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > ---
> >  scripts/kernel-doc.py | 32 ++++++++++++++++++++++----------
> >  1 file changed, 22 insertions(+), 10 deletions(-)
> >
> > diff --git a/scripts/kernel-doc.py b/scripts/kernel-doc.py
> > index 7a1eaf986bcd..600bdfea6a96 100755
> > --- a/scripts/kernel-doc.py
> > +++ b/scripts/kernel-doc.py
> > @@ -176,7 +176,14 @@ class MsgFormatter(logging.Formatter):
> >          return logging.Formatter.format(self, record)
> >  
> >  def main():
> > -    """Main program"""
> > +    """
> > +    Main program
> > +    By default, the return value is zero on parsing errors or when the
> > +    Python version is not compatible with kernel-doc. The rationale is
> > +    to not break Linux compilation on such cases.
> > +    If -Werror is used, it will return the number of parse errors, up to
> > +    255 errors, as this is the maximum value allowed by glibc.
> > +    """
> >  
> >      parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter,
> >                                       description=DESC)
> > @@ -321,18 +328,23 @@ def main():
> >      if not error_count:
> >          sys.exit(0)
> >  
> > +    if args.verbose:
> > +        print("%s errors" % error_count)                # pylint: disable=C0209
> > +
> > +
> >      if args.werror:
> >          print("%s warnings as errors" % error_count)    # pylint: disable=C0209
> > +
> > +        #
> > +        # Return code is 8-bits, as seen at:
> > +        #   https://www.gnu.org/software/libc/manual/html_node/Exit-Status.html
> > +        # Truncate to avoid overflow
> > +        #
> > +        if error_count > 255:
> > +            error_count = 255
> 
> What's the point in returning the error count anyway?

Mostly historical reasons. I used the return value during the conversion
to help verifying if the Python version was doing the right thing.

> I'd rather see some error/warning classification in the exit code than a
> count. Like, the argparser uses exit code 2 by default, so you can't
> even trust the exit code to return the count anyway.

Right now, python can exit with:

1. argparse errors;

2. sys.exit() with messages like:
    sys.exit(f"Error running fc-list: {repr(exc)}")

3. eventually unhandled errors that would rise

4. sys.exit(0) if:
    - No warnings;
    - the -Werror is not used and warnings were issued;
    - Python version < 3.6 (we want kernel to keep building)

5. error count > 0

(2) and (3) returns 1; argparse returns 2.

So, maybe we can use sys.exit(3) for warnings.

-- 
Thanks,
Mauro