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From:   Michal Suchanek <msuchanek@suse.de>
To:     linux-modules@vger.kernel.org
Cc:     Michal Suchanek <msuchanek@suse.de>, Takashi Iwai <tiwai@suse.com>,
        Lucas De Marchi <lucas.de.marchi@gmail.com>,
        =?UTF-8?q?Michal=20Koutn=C3=BD?= <mkoutny@suse.com>,
        Jiri Slaby <jslaby@suse.com>, Jan Engelhardt <jengelh@inai.de>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v6 1/2] depmod: Handle installing modules under a different directory
Date:   Wed,  6 Dec 2023 20:47:51 +0100
Message-ID: <32b332af189bfca8acdb231cee294355aa4af290.1701892062.git.msuchanek@suse.de>
In-Reply-To: <CAK7LNAT3N82cJD3GsF+yUBEfPNOBkhzYPk37q3k0HdU7ukz9vQ@mail.gmail.com>
References: <CAK7LNAT3N82cJD3GsF+yUBEfPNOBkhzYPk37q3k0HdU7ukz9vQ@mail.gmail.com>
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Some distributions aim at shipping all files in /usr.

The path under which kernel modules are installed is hardcoded to /lib
which conflicts with this goal.

When kmod provides kmod.pc, use it to determine the correct module
installation path.

With kmod that does not provide the config /lib/modules is used as
before.

While pkg-config does not return an error when a variable does not exist
the kmod configure script puts some effort into ensuring that
module_directory is non-empty. With that empty module_directory from
pkg-config can be used to detect absence of the variable.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
v6:
 - use ?= instead of := to make it easier to override the value
 - use shorter expression for determining the module directory assuming
   it's non-empty
---
 Makefile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 511b5616aa41..84f32bd563d4 100644
--- a/Makefile
+++ b/Makefile
@@ -1081,7 +1081,9 @@ export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)
 # makefile but the argument can be passed to make if needed.
 #
 
-MODLIB	= $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
+export KERNEL_MODULE_DIRECTORY ?= $(or $(shell pkg-config --variable=module_directory kmod 2>/dev/null),/lib/modules)
+
+MODLIB	= $(INSTALL_MOD_PATH)$(KERNEL_MODULE_DIRECTORY)/$(KERNELRELEASE)
 export MODLIB
 
 PHONY += prepare0
-- 
2.42.0