Re: [PATCH v3 07/16] kbuild: introduce blob framework

From: Masahiro Yamada <masahiroy@kernel.org>
To: "Thomas Weißschuh" <thomas.weissschuh@linutronix.de>
Cc: "Nathan Chancellor" <nathan@kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Willy Tarreau" <w@1wt.eu>,
	"Thomas Weißschuh" <linux@weissschuh.net>,
	"Brendan Higgins" <brendan.higgins@linux.dev>,
	"David Gow" <davidgow@google.com>, "Rae Moar" <rmoar@google.com>,
	"Shuah Khan" <shuah@kernel.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Nicolas Schier" <nicolas.schier@linux.dev>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	"Christophe Leroy" <christophe.leroy@csgroup.eu>,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
	linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org,
	workflows@vger.kernel.org
Subject: Re: [PATCH v3 07/16] kbuild: introduce blob framework
Date: Tue, 17 Jun 2025 00:38:21 +0900	[thread overview]
Message-ID: <CAK7LNARYXKq9KyCczcY_VjwQG3QWEufV1McayHDnavvuU+JEhQ@mail.gmail.com> (raw)
In-Reply-To: <20250611-kunit-kselftests-v3-7-55e3d148cbc6@linutronix.de>

On Wed, Jun 11, 2025 at 4:38 PM Thomas Weißschuh
<thomas.weissschuh@linutronix.de> wrote:
>
> Various subsystems embed non-code build artifacts into the kernel,
> for example the initramfs, /proc/config.gz, vDSO image, etc.
> Currently each user has their own implementation for that.
>
> Add a common "blob" framework to provide this functionality.
> It provides standard kbuild and C APIs to embed and later access non-code
> build artifacts into the kernel image or modules.
>
> Reviewed-by: Nicolas Schier <n.schier@avm.de>
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>

Kbuild provides only a small set of syntaxes, yet it's flexible enough
to allow each Makefile to implement what it needs.
I aim to keep Kbuild scripts as simple as possible and avoid over-engineering.

Instead, you can implement this in lib/kunit/Makefile.kunit-uapi or somewhere.
That way, I do not have to be worried about what you do.

Also, your separate blob approach looks questionable to me.
In your approach, the blob (kunit-example-uapi.blob.o)
and the entry point (kunit-example-test.o) can be separate modules.
The entry point would be a small amount of boilerplate.
I would keep the user-program blob and its entry point in the same C file.
(and I may consider writing a macro for populating a blob + knit entry)

> ---
> Due to its closeness to kbuild this is currently added to its MAINTAINER entry.
> But I can also maintain it on its own.

Or, maybe do not add this.

-- 
Best Regards
Masahiro Yamada

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