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Message-ID: <1536720f-7fba-4c47-8708-bfa80b701e7a@infradead.org>
Date: Fri, 5 Apr 2024 10:19:08 -0700
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Subject: Re: [PATCH v3] Add MO(mod objs) variable to process ext modules with
 subdirs
To: Valerii Chernous <vchernou@cisco.com>,
 Masahiro Yamada <masahiroy@kernel.org>, Nathan Chancellor
 <nathan@kernel.org>, Nicolas Schier <nicolas@fjasle.eu>
Cc: xe-linux-external@cisco.com, Jonathan Corbet <corbet@lwn.net>,
 linux-kbuild@vger.kernel.org, linux-doc@vger.kernel.org,
 linux-kernel@vger.kernel.org
References: <20240405165610.1537698-1-vchernou@cisco.com>
Content-Language: en-US
From: Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <20240405165610.1537698-1-vchernou@cisco.com>
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Hi Valerii,

On 4/5/24 9:56 AM, Valerii Chernous wrote:
> The change allow to build external modules with nested makefiles.
> With current unofficial way(using "src" variable) it is possible to build
> external(out of tree) kernel module with separate source and build
> artifacts dirs but with nested makefiles it doesn't work properly.
> Build system trap to recursion inside makefiles, artifacts output dir
> path grow with each iteration until exceed max path len and build failed.
> Providing "MO" variable and using "override" directive with declaring
> "src" variable solves the problem
> Usage example:
> make -C KERNEL_SOURCE_TREE MO=BUILD_OUT_DIR M=EXT_MOD_SRC_DIR modules
> 
> Cc: xe-linux-external@cisco.com
> Cc: Valerii Chernous <vchernou@cisco.com>
> Signed-off-by: Valerii Chernous <vchernou@cisco.com>
> ---
>  Documentation/kbuild/kbuild.rst  | 14 +++++++++++++-
>  Documentation/kbuild/modules.rst | 16 +++++++++++++++-
>  Makefile                         | 17 +++++++++++++++++
>  scripts/Makefile.build           |  7 +++++++
>  4 files changed, 52 insertions(+), 2 deletions(-)
> 

I can read it now. There are still a few small things that I would
change, but they aren't a big deal.

I'll leave it for Masahiro or others to comment on.

Thanks.
-- 
#Randy