Fix "make install" with DESTDIR set

[kohlschuetter]

"DESTDIR=/path/to/target/root/ make install" may fail when installing to a root that contains an existing lib/modules structure. When run as root we may even affect the wrong kernel (the build system's one, or, if running a different version, some other directory in /lib/modules, but not the desired one installed in DESTDIR).

Add a missing reference to the INSTALL_MOD_PATH root when calling "depmod" during "make install"

Also add a switch "DONT_DELETE_MODULES_FILES=1" that skips the removal of files named "modules.*" prior to running depmod.

Signed-off-by: Christian Kohlschütter [email protected]
Closes #16994

Motivation and Context

Fixes an important build issue when installing to DESTDIR.
see issue #16994

Description

In addition to the details in #16994:

I'm sure there's a reason why the current makefile deletes files starting with "modules.*", so I'm only adding a switch that can disable that functionality when not desired.

With this change, I can now install zfs nto my target root as follows:

DONT_DELETE_MODULES_FILES=1 DESTDIR=/tmp/kernel-out make install

How Has This Been Tested?

Tested on Alpine Linux 3.21.2 using the following zfs build instructions

#KERNEL_DIR=/path/to/kernel/source
#KERNEL_OUT=/path/to/target/root
./configure --prefix=/usr \
			--with-tirpc \
			--sysconfdir=/etc \
			--mandir=/usr/share/man \
			--infodir=/usr/share/info \
			--localstatedir=/var \
			--with-config=kernel \
			--with-linux="$KERNEL_DIR"
make -s -j$(nproc)
DONT_DELETE_MODULES_FILES=1 DESTDIR="$KERNEL_OUT" make install

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied. (NOTE: unrelated since it's an integration issue)
• All commit messages are properly formatted and contain Signed-off-by.

[robn]

Nice. I've had a similar workaround (the -b part) for over a year for my local dev VMs. I have no opinion on the "don't delete" flag other than its useful and nonintrusive.

[behlendorf]

I'm fairly sure we added this originally to avoid adding extraneous files to deb and rpm packages. I'm fine with not changing the behavior for now, but maybe the thing to do is flip this login around and set a flag so we only purge this extra files when building a package.

[kohlschuetter]

Unless you have strong objections, I'd suggest flipping this logic at a later point. This will allow the fix to get merged now, without causing any unexpected side-effects. The logic flip would have to be communicated with integrators, so it's probably best to do that aligned with a major release.

[tonyhutter]

For what it's worth, I test built RPMs with both vanilla master and with this PR, and the RPM filelists were the same.