From: Masahiro Yamada <masahiroy@kernel.org>
To: "Michal Suchánek" <msuchanek@suse.de>
Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
"Nicolas Schier" <nicolas@fjasle.eu>,
linux-modules@vger.kernel.org, "Takashi Iwai" <tiwai@suse.com>,
"Lucas De Marchi" <lucas.de.marchi@gmail.com>,
"Michal Koutný" <mkoutny@suse.com>,
"Jiri Slaby" <jslaby@suse.com>,
"Jan Engelhardt" <jengelh@inai.de>,
"Nathan Chancellor" <nathan@kernel.org>,
"Nick Desaulniers" <ndesaulniers@google.com>
Subject: Re: [PATCH rebased] kbuild: rpm-pkg: Fix build with non-default MODLIB
Date: Tue, 17 Oct 2023 19:15:50 +0900 [thread overview]
Message-ID: <CAK7LNASX2_-xt3Qvxie_G=Q4fuVYR6eE47QjQ5NZf7QxY-4_tQ@mail.gmail.com> (raw)
In-Reply-To: <20231010101552.GW6241@kitsune.suse.cz>
> >
> > Let me add more context to my question.
> >
> >
> > I am interested in the timing when
> > 'pkg-config --print-variables kmod | grep module_directory'
> > is executed.
> >
> >
> >
> > 1. Build a SRPM on machine A
> >
> > 2. Copy the SRPM from machine A to machine B
> >
> > 3. Run rpmbuild on machine B to build the SRPM into a RPM
> >
> > 4. Copy the RPM from machine B to machine C
> >
> > 5. Install the RPM to machine C
>
> As far as I am aware the typical use case is two step:
>
> 1. run make rpm-pkg on machine A
> 2. install the binary rpm on machine C that might not have build tools
> or powerful enough CPU
>
> While it's theoretically possible to use the srpm to rebuild the binary
> rpm independently of the kernel git tree I am not aware of people
> commonly doing this.
If I correctly understand commit
8818039f959b2efc0d6f2cb101f8061332f0c77e,
those Redhat guys pack a SRPM on a local machine,
then send it to their build server called 'koji'.
Otherwise, there is no reason
to have 'make srcrpm-pkg'.
I believe "A == B" is not always true,
but we can assume "distro(A) == distro(B)" is always met
for simplicity.
So, I am OK with configuration at the SRPM time.
> If rebuilding the source rpm on a different machine from where the git
> tree is located, and possibly on a different distribution is desirable
> then the detection of the KERNEL_MODULE_DIRECTORY should be added in the
> rpm spec file as well.
>
> > Of course, we are most interested in the module path
> > of machine C, but it is difficult/impossible to
> > guess it at the time of building.
> >
> > We can assume machine B == machine C.
> >
> > We are the second most interested in the module
> > path on machine B.
> >
> > The module path of machine A is not important.
> >
> > So, I am asking where you would inject
> > 'pkg-config --print-variables kmod | grep module_directory'.
>
> I don't. I don't think there will be a separate machine B.
>
> And I can't really either - so far any attempt at adding support for
> this has been rejected.
>
> Technically the KERNEL_MODULE_DIRECTORY could be set in two steps - one
> giving the script to run, and one running it, and then it could be run
> independently in the SRPM as well.
At first, I thought your patch [1] was very ugly,
but I do not think it is so ugly if cleanly implemented.
It won't hurt to allow users to specify the middle part of MODLIB.
There are two options.
[A] Add 'MOD_PREFIX' to specify the middle part of MODLIB
The top Makefile will look as follows:
MODLIB = $(INSTALL_MOD_PATH)$(MOD_PREFIX)/lib/modules/$(KERNELRELEASE)
export MODLIB
It is easier than specifying the entire MODLIB, but you still need
to manually pass "MOD_PREFIX=/usr" from an env variable or
the command line.
If MOD_PREFIX is not given, MODLIB is the same as the current one.
[B] Support a dynamic configuration as well
MOD_PREFIX ?= $(shell pkg-config --variable=module_prefix libkmod 2>/dev/null)
export MOD_PREFIX
MODLIB = $(INSTALL_MOD_PATH)$(MOD_PREFIX)/lib/modules/$(KERNELRELEASE)
export MODLIB
If MOD_PREFIX is given from an env variable or from the command line,
it is respected.
If "pkg-config --variable=module_prefix libkmod" works,
that configuration is applied.
Otherwise, MOD_PREFIX is empty, i.e. fall back to the current behavior.
I prefer 'MOD_PREFIX' to 'KERNEL_MODULE_DIRECTORY' in your patch [1]
because "|| echo /lib/modules" can be omitted.
I do not think we will have such a crazy distro that
installs modules under /opt/ directory.
I could not understand why you inserted
"--print-variables kmod 2>/dev/null | grep '^module_directory$$' >/dev/null"
but I guess the reason is the same.
"pkg-config --variable=module_directory kmod" always succeeds,
so "|| echo /lib/modules" is never processed.
I do not know why you parsed kmod.pc instead of libkmod.pc [2]
[1] https://lore.kernel.org/linux-kbuild/20230718120348.383-1-msuchanek@suse.de/
[2] https://github.com/kmod-project/kmod/blob/v31/configure.ac#L295
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2023-10-17 10:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-05 15:07 [PATCH rebased] kbuild: rpm-pkg: Fix build with non-default MODLIB Michal Suchanek
2023-10-06 16:58 ` Nathan Chancellor
2023-10-09 8:31 ` Masahiro Yamada
2023-10-09 8:52 ` Michal Suchánek
2023-10-09 12:34 ` Masahiro Yamada
2023-10-09 14:07 ` Michal Suchánek
2023-10-09 15:14 ` Masahiro Yamada
2023-10-09 16:01 ` Jan Engelhardt
2023-10-10 10:15 ` Michal Suchánek
2023-10-17 10:15 ` Masahiro Yamada [this message]
2023-10-17 10:44 ` Michal Suchánek
2023-10-17 12:05 ` Masahiro Yamada
2023-10-17 12:27 ` Michal Suchánek
2023-10-17 14:46 ` Masahiro Yamada
2023-10-17 15:10 ` Michal Suchánek
2023-10-18 1:12 ` Jan Engelhardt
2023-11-10 17:44 ` Michal Suchánek
2023-11-10 17:57 ` Jan Engelhardt
2023-12-06 19:47 ` [PATCH v6 1/2] depmod: Handle installing modules under a different directory Michal Suchanek
2023-12-10 18:43 ` Masahiro Yamada
2023-12-10 18:51 ` Woody Suwalski
2023-12-10 21:07 ` Michal Suchánek
2023-12-11 4:29 ` Masahiro Yamada
2023-12-12 13:03 ` Michal Suchánek
2023-12-18 14:05 ` Masahiro Yamada
2023-12-06 19:47 ` [PATCH v6 2/2] kbuild: rpm-pkg: Fix build with non-default MODLIB Michal Suchanek
2023-12-10 18:44 ` Masahiro Yamada
2023-12-10 21:08 ` Michal Suchánek
2023-12-11 4:33 ` Masahiro Yamada
2023-12-12 13:12 ` Michal Suchánek
2023-12-18 14:16 ` Masahiro Yamada
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