On Tue, Jul 18, 2023 at 04:14:11AM +0900, Masahiro Yamada wrote:

On Sat, Jul 15, 2023 at 12:10 AM Michal Suchánek [off-list ref] wrote:

quoted

On Fri, Jul 14, 2023 at 04:54:49PM +0200, Nicolas Schier wrote:

quoted

On Fri, Jul 14, 2023 at 04:30:02PM +0200, Michal Such�nek wrote:

quoted

Hello,

On Fri, Jul 14, 2023 at 04:05:10PM +0200, Nicolas Schier wrote:

quoted

On Fri, Jul 14, 2023 at 02:21:08PM +0200 Michal Suchanek wrote:

quoted

Some distributions aim at not shipping any files in / outside of usr.

For me, preventing negation often makes things easier, e.g.: "... aim at
shipping files only below /usr".

quoted

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

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

This is a prefix under which the modules are searched by kmod on the
system, and is separate from the temporary staging location already
supported by INSTALL_MOD_PATH.

With kmod that does not provide the config command empty prefix is used
as before.

Signed-off-by: Michal Suchanek <redacted>
---
v2: Avoid error on systems with kmod that does not support config
command
v3: More verbose commit message
---
 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)

All other calls of `jq` that I could find are located at tools/; as this here
is evaluated on each invocation, this should probably be documented in
Documentation/process/changes.rst?

(Absence of `jq` will cause error messages, even with CONFIG_MODULES=n.)

That's a good point.

quoted

quoted

+
+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

I'd like to come back to the statement from Masahiro: Is the check above,
against some very old versions of depmod [1], the only reason for this patch?

If we could remove that, would

    make INSTALL_MOD_PATH="$(kmod config | jq -r .module_prefix)" modules_install

be sufficient?

No, the INSTALL_MOD_PATH is passed as the -b argument to depmod while
the newly added part is not because it's integral part of where the
modules are installed on the system, and not the staging area path.

Ah, thanks.  So just for my understanding, could this be a (non-gentle)
alternative version of your patch, w/o modifying top-level Makefile?

diff --git a/scripts/depmod.sh b/scripts/depmod.sh
index 3643b4f896ed..72c819de0669 100755
--- a/scripts/depmod.sh
+++ b/scripts/depmod.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 #
 # A depmod wrapper used by the toplevel Makefile

@@ -23,6 +23,8 @@ if [ -z $(command -v $DEPMOD) ]; then
        exit 0
 fi

+kmod_version=$(( $(kmod --version | sed -rne 's/^kmod version ([0-9]+).*$/\1/p') ))
+
 # older versions of depmod require the version string to start with three
 # numbers, so we cheat with a symlink here
 depmod_hack_needed=true

@@ -35,6 +37,13 @@ if "$DEPMOD" -b "$tmp_dir" $KERNELRELEASE 2>/dev/null; then
        fi
 fi
 rm -rf "$tmp_dir"
+
+if [ "${kmod_version}" -gt 32 ]; then
+       kmod_prefix="$(kmod config | jq -r .module_prefix)"
+       INSTALL_MOD_PATH="${INSTALL_MOD_PATH#${kmod_prefix}"
+       depmod_hack_needed=false
+fi
+
 if $depmod_hack_needed; then
        symlink="$INSTALL_MOD_PATH/lib/modules/99.98.$KERNELRELEASE"
        ln -s "$KERNELRELEASE" "$symlink"

(untested, and assuming that kmod module prefix is in kmod >= 32)

It can be detected by running the 'kmod config' command first and
ignoring the output when it fails which the above patch already did.
The version check does not sound very reliable.

quoted

Or are I am still missing something?

MODLIB still needs to include the extra prefix so that files are
installed in the correct location. And that's defined in the toplevel
Makefile.

Thanks

Michal

As Documentation/kbuild/kbuild.rst mentions,
you can override MODLIB.

Kbuild already provides the maximum flexibility.


$ make modules_install \
  INSTALL_MOD_PATH=/path/to/whatever/staging/dir \
  MODLIB=/path/to/whatever/real/install/destination

That's great that we have another workaround for the case when the
kernel build system and kmod do not agree on the location of the kernel
modules.

However, they should by default agree, and if this feature is merged
into kmod the kernel should also adapt to make sure the modules are
installed where kmod expects them.

Thanks

Michal