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

From: Jiri Slaby <jirislaby@kernel.org>
To: Michal Suchanek <msuchanek@suse.de>, linux-modules@vger.kernel.org
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
Subject: Re: [PATCH] depmod: Handle installing modules under a prefix
Date: Wed, 12 Jul 2023 07:47:13 +0200	[thread overview]
Message-ID: <da2fdd15-fae1-2bf6-04e7-568c715372ce@kernel.org> (raw)
In-Reply-To: <20230711153457.29497-1-msuchanek@suse.de>

On 11. 07. 23, 17:34, Michal Suchanek wrote:
> Some distributions aim at not shipping any files in / ustside of usr.
> 
> The path under which kernel modules are instaleld is hardcoded to /lib
> 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.
> 
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> ---
>   Makefile          | 4 +++-
>   scripts/depmod.sh | 8 ++++----
>   2 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 47690c28456a..b05d696f06bd 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 | jq -r .module_prefix)

echo -e 'KERNEL_MODULE_PREFIX := $(shell kmod config | jq -r 
.module_prefix)\nall:'|make -f -
invalid command 'config'
parse error: Invalid numeric literal at line 1, column 5

I think you should pipe kmod's 2> /dev/null to support older kmod. Ah, 
but you'd need 2> /dev/null for jq too. That would not be good as jq 
might not be installed and a user wouldn't see the error. So instead, I 
would do:

$(shell kmod config &> /dev/null && kmod config | jq -r .module_prefix)

thanks,
-- 
js
suse labs