Re: [PATCH v2] depmod: Handle installing modules under a prefix

From: Jiri Slaby <jslaby@suse.com>
To: Michal Suchanek <msuchanek@suse.de>
Cc: "Takashi Iwai" <tiwai@suse.com>,
	"Lucas De Marchi" <lucas.de.marchi@gmail.com>,
	"Michal Koutný" <mkoutny@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,
	linux-modules@vger.kernel.org
Subject: Re: [PATCH v2] depmod: Handle installing modules under a prefix
Date: Fri, 14 Jul 2023 08:25:31 +0200	[thread overview]
Message-ID: <30d8c675-e769-e567-a81f-c1b59c66ad67@suse.com> (raw)
In-Reply-To: <20230712134533.4419-1-msuchanek@suse.de>

On 12. 07. 23, 15:45, Michal Suchanek wrote:
> Some distributions aim at not shipping any files in / ustside of usr.

"outside".

> The path under which kernel modules are instaleld is hardcoded to /lib

"installed"

> which conflicts with this goal.
> 
> When kmod provides the config command use it to determine the correct
> module installation prefix.
> 
> On kmod that does not provide the command / is used as before.

Can you spice it with more commas? While the text is understandable 
after a while of staring, it's hard to parse.

Like:
When kmod provides the config command, use it to determine the correct 
module installation prefix.

On kmod that does not provide the command, / is used as before.

I would also argue here in the commit log on what Masahiro already 
pointed out. I.e. that INSTALL_MOD_PATH is useless in this case and why.

> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> ---
> v2: Avoid error on systems with kmod that does not support config
> command
> ---
>   Makefile          | 4 +++-
>   scripts/depmod.sh | 8 ++++----
>   2 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 47690c28456a..b1fea135bdec 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1165,7 +1165,9 @@ 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_PREFIX := $(shell kmod config &> /dev/null && kmod config | jq -r .module_prefix)
> +
> +MODLIB	= $(INSTALL_MOD_PATH)$(KERNEL_MODULE_PREFIX)/lib/modules/$(KERNELRELEASE)
>   export MODLIB
>   
>   PHONY += prepare0
> diff --git a/scripts/depmod.sh b/scripts/depmod.sh
> index 3643b4f896ed..88ac79056153 100755
> --- a/scripts/depmod.sh
> +++ b/scripts/depmod.sh
> @@ -27,16 +27,16 @@ fi
>   # numbers, so we cheat with a symlink here
>   depmod_hack_needed=true
>   tmp_dir=$(mktemp -d ${TMPDIR:-/tmp}/depmod.XXXXXX)
> -mkdir -p "$tmp_dir/lib/modules/$KERNELRELEASE"
> +mkdir -p "$tmp_dir$KERNEL_MODULE_PREFIX/lib/modules/$KERNELRELEASE"
>   if "$DEPMOD" -b "$tmp_dir" $KERNELRELEASE 2>/dev/null; then
> -	if test -e "$tmp_dir/lib/modules/$KERNELRELEASE/modules.dep" -o \
> -		-e "$tmp_dir/lib/modules/$KERNELRELEASE/modules.dep.bin"; then
> +	if test -e "$tmp_dir$KERNEL_MODULE_PREFIX/lib/modules/$KERNELRELEASE/modules.dep" -o \
> +		-e "$tmp_dir$KERNEL_MODULE_PREFIX/lib/modules/$KERNELRELEASE/modules.dep.bin"; then
>   		depmod_hack_needed=false
>   	fi
>   fi
>   rm -rf "$tmp_dir"
>   if $depmod_hack_needed; then
> -	symlink="$INSTALL_MOD_PATH/lib/modules/99.98.$KERNELRELEASE"
> +	symlink="$INSTALL_MOD_PATH$KERNEL_MODULE_PREFIX/lib/modules/99.98.$KERNELRELEASE"
>   	ln -s "$KERNELRELEASE" "$symlink"
>   	KERNELRELEASE=99.98.$KERNELRELEASE
>   fi

-- 
js
suse labs