From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Jani Nikula <jani.nikula@intel.com>
Cc: Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
intel-gfx@lists.freedesktop.org,
Chris Wilson <chris@chris-wilson.co.uk>,
Michal Marek <michal.lkml@markovi.net>
Subject: Re: [RFC 1/3] kbuild: add support for ensuring headers are self-contained
Date: Sat, 18 May 2019 14:16:50 +0900 [thread overview]
Message-ID: <CAK7LNAQv-fm2iV6HW_FM0Fe6hNDeJ25c9CS2SbroSOneoepFMQ@mail.gmail.com> (raw)
In-Reply-To: <20190516194818.29230-1-jani.nikula@intel.com>
On Fri, May 17, 2019 at 4:48 AM Jani Nikula <jani.nikula@intel.com> wrote:
>
> Sometimes it's useful to be able to explicitly ensure certain headers
> remain self-contained, i.e. that they are compilable as standalone
> units, by including and/or forward declaring everything they depend on.
>
> Add special target header-test-y where individual Makefiles can add
> headers to be tested if CONFIG_HEADER_TEST is enabled. This will
> generate a dummy C file per header that gets built as part of extra-y.
>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Cc: Michal Marek <michal.lkml@markovi.net>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
> Documentation/kbuild/makefiles.txt | 7 +++++++
> init/Kconfig | 9 +++++++++
> scripts/Makefile.build | 10 ++++++++++
> scripts/Makefile.lib | 3 +++
> 4 files changed, 29 insertions(+)
>
> diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
> index 03c065855eaf..73df58e5ea0c 100644
> --- a/Documentation/kbuild/makefiles.txt
> +++ b/Documentation/kbuild/makefiles.txt
> @@ -1036,6 +1036,13 @@ When kbuild executes, the following steps are followed (roughly):
> In this example, extra-y is used to list object files that
> shall be built, but shall not be linked as part of built-in.a.
>
> + header-test-y
> +
> + header-test-y specifies headers (*.h) in the current directory that
> + should be compile tested to ensure they are self-contained,
> + i.e. compilable as standalone units. If CONFIG_HEADER_TEST is enabled,
> + this autogenerates dummy sources to include the headers, and builds them
> + as part of extra-y.
>
> --- 6.7 Commands useful for building a boot image
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 4592bf7997c0..d91b157201b1 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -95,6 +95,15 @@ config COMPILE_TEST
> here. If you are a user/distributor, say N here to exclude useless
> drivers to be distributed.
>
> +config HEADER_TEST
> + bool "Compile test headers that should be standalone compilable"
> + help
> + Compile test headers listed in header-test-y target to ensure they are
> + self-contained, i.e. compilable as standalone units.
> +
> + If you are a developer or tester and want to ensure the requested
> + headers are self-contained, say Y here. Otherwise, choose N.
> +
> config LOCALVERSION
> string "Local version - append to kernel release"
> help
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 76ca30cc4791..4d4bf698467a 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -291,6 +291,16 @@ quiet_cmd_cc_lst_c = MKLST $@
> $(obj)/%.lst: $(src)/%.c FORCE
> $(call if_changed_dep,cc_lst_c)
>
> +# Dummy C sources for header test (header-test-y target)
> +# ---------------------------------------------------------------------------
> +
> +quiet_cmd_header_test = HDRTEST $@
> + cmd_header_test = echo "\#include \"$(<F)\"" > $@
> +
> +# FIXME: would be nice to be able to limit this implicit rule to header-test-y
> +$(obj)/%.header_test.c: $(src)/%.h FORCE
> + $(call if_changed,header_test)
> +
> # Compile assembler sources (.S)
> # ---------------------------------------------------------------------------
>
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 8a1f64f17740..c2839de06485 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -66,6 +66,9 @@ extra-y += $(patsubst %.dtb,%.dt.yaml, $(dtb-y))
> extra-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtb,%.dt.yaml, $(dtb-))
> endif
>
> +# Test self-contained headers
> +extra-$(CONFIG_HEADER_TEST) += $(patsubst %.h,%.header_test.o,$(header-test-y))
> +
> # Add subdir path
>
> extra-y := $(addprefix $(obj)/,$(extra-y))
> --
> 2.20.1
>
Thanks, probably we should do this.
At least, this check will be useful
for uapi headers since the kernel does not
test the self-containedness of
exported headers, (then turned out be problematic
later in user-space).
I will take a little time to considier
how far we can extend the idea about
"headers should be self-contained".
Thank you.
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2019-05-18 5:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-16 19:48 [RFC 1/3] kbuild: add support for ensuring headers are self-contained Jani Nikula
2019-05-16 19:48 ` [RFC 2/3] drm/i915: ensure headers remain self-contained Jani Nikula
2019-05-16 19:48 ` [RFC 3/3] DO NOT MERGE: drm/i915: add failing header to header-test-y Jani Nikula
2019-05-17 8:35 ` [RFC 1/3] kbuild: add support for ensuring headers are self-contained Chris Wilson
2019-05-18 5:29 ` Masahiro Yamada
2019-05-18 5:16 ` Masahiro Yamada [this message]
2019-05-20 9:20 ` [Intel-gfx] " Jani Nikula
2019-06-03 17:16 ` Masahiro Yamada
2019-05-24 17:40 ` Sam Ravnborg
2019-06-03 17:05 ` Masahiro Yamada
2019-06-03 17:33 ` Sam Ravnborg
2019-06-04 0:20 ` Masahiro Yamada
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