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From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kbuild@vger.kernel.org
Subject: [PATCH v4 12/14] kbuild: make *.mod rule robust against too long
 argument error
Date: Mon,  9 May 2022 04:06:29 +0900
Message-Id: <20220508190631.2386038-13-masahiroy@kernel.org>
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Cc: linux-s390@vger.kernel.org, Nicolas Schier <nicolas@fjasle.eu>,
 Peter Zijlstra <peterz@infradead.org>, Masahiro Yamada <masahiroy@kernel.org>,
 Nick Desaulniers <ndesaulniers@google.com>, linux-kernel@vger.kernel.org,
 Nathan Chancellor <nathan@kernel.org>, clang-built-linux@googlegroups.com,
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 Ard Biesheuvel <ardb@kernel.org>, linux-modules@vger.kernel.org
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 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

Like built-in.a, the command length of the *.mod rule scales with
the depth of the directory times the number of objects in the Makefile.

Add $(obj)/ by the shell command (awk) instead of by Make's builtin
function.

In-tree modules still have some room to the limit (ARG_MAX=2097152),
but this is more future-proof for big modules in a deep directory.

For example, you can build i915 as a module (CONFIG_DRM_I915=m) and
compare drivers/gpu/drm/i915/.i915.mod.cmd with/without this commit.

The issue is more critical for external modules because the M= path
can be very long as Jeff Johnson reported before [1].

[1] https://lore.kernel.org/linux-kbuild/4c02050c4e95e4cb8cc04282695f8404@codeaurora.org/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
---

(no changes since v2)

Changes in v2:
  - New patch

 scripts/Makefile.build | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 8f1a355df7aa..f546b5f1f33f 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -270,8 +270,8 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
 	$(call if_changed_rule,cc_o_c)
 	$(call cmd,force_checksrc)
 
-cmd_mod = echo $(addprefix $(obj)/, $(call real-search, $*.o, .o, -objs -y -m)) | \
-	$(AWK) -v RS='( |\n)' '!x[$$0]++' > $@
+cmd_mod = echo $(call real-search, $*.o, .o, -objs -y -m) | \
+	$(AWK) -v RS='( |\n)' '!x[$$0]++ { print("$(obj)/"$$0) }' > $@
 
 $(obj)/%.mod: FORCE
 	$(call if_changed,mod)
-- 
2.32.0


From mboxrd@z Thu Jan  1 00:00:00 1970
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From:   Masahiro Yamada <masahiroy@kernel.org>
To:     linux-kbuild@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        Peter Zijlstra <peterz@infradead.org>,
        linux-modules@vger.kernel.org, linux-s390@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, clang-built-linux@googlegroups.com,
        Ard Biesheuvel <ardb@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Masahiro Yamada <masahiroy@kernel.org>
Subject: [PATCH v4 12/14] kbuild: make *.mod rule robust against too long argument error
Date:   Mon,  9 May 2022 04:06:29 +0900
Message-Id: <20220508190631.2386038-13-masahiroy@kernel.org>
X-Mailer: git-send-email 2.32.0
In-Reply-To: <20220508190631.2386038-1-masahiroy@kernel.org>
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MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk
List-ID: <linux-modules.vger.kernel.org>

Like built-in.a, the command length of the *.mod rule scales with
the depth of the directory times the number of objects in the Makefile.

Add $(obj)/ by the shell command (awk) instead of by Make's builtin
function.

In-tree modules still have some room to the limit (ARG_MAX=2097152),
but this is more future-proof for big modules in a deep directory.

For example, you can build i915 as a module (CONFIG_DRM_I915=m) and
compare drivers/gpu/drm/i915/.i915.mod.cmd with/without this commit.

The issue is more critical for external modules because the M= path
can be very long as Jeff Johnson reported before [1].

[1] https://lore.kernel.org/linux-kbuild/4c02050c4e95e4cb8cc04282695f8404@codeaurora.org/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
---

(no changes since v2)

Changes in v2:
  - New patch

 scripts/Makefile.build | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 8f1a355df7aa..f546b5f1f33f 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -270,8 +270,8 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
 	$(call if_changed_rule,cc_o_c)
 	$(call cmd,force_checksrc)
 
-cmd_mod = echo $(addprefix $(obj)/, $(call real-search, $*.o, .o, -objs -y -m)) | \
-	$(AWK) -v RS='( |\n)' '!x[$$0]++' > $@
+cmd_mod = echo $(call real-search, $*.o, .o, -objs -y -m) | \
+	$(AWK) -v RS='( |\n)' '!x[$$0]++ { print("$(obj)/"$$0) }' > $@
 
 $(obj)/%.mod: FORCE
 	$(call if_changed,mod)
-- 
2.32.0