On Fri, Aug 18, 2023 at 12:15 PM Michal Suchánek [off-list ref] wrote:

Hello,

On Tue, Jul 18, 2023 at 02:01:51PM +0200, Michal Suchanek wrote:

quoted

Hello,

with these patches it is possible to install kernel modules in an arbitrary
directory - eg. moving the /lib/modules to /usr/lib/modules or /opt/linux.

While the modprobe.d and depmod.d search which already includes multiple
paths is expanded to also include $(prefix) the module directory still
supports only one location, only a different one under $(module_directory).

Having kmod search multiple module locations while only one is supported now
might break some assumption about relative module path corresponding to a
specific file, would require more invasive changes to implement, and is not
supportive of the goal of moving the modules away from /lib.

Both kmod and the kernel need to be patched to make use of this feature.
Patched kernel is backwards compatible with older kmod.  Patched kmod
with $(module_directory) set to /lib/modules is equivalent to unpatched kmod.

The patch to kernel to support autodetection of module directory is
rejected. However, a workaround like

make MODLIB='$(INSTALL_MOD_PATH)/usr/lib/modules/$(KERNELRELEASE)'

is suggested.

Can you consider inluding the kmod changes?

Hi.

I have a question about your original patch
for the Kbuild change.

In your patch, Kbuild runs 'kmod config' or
'pkg-config --variable=module_directory kmod',
then sets the returned string to MODLIB.


If kmod is configured to use /usr/lib/modules,
/opt/modules, or whatever,
should we change the installation path of the debug
vdso accordingly?

Currently, the debug vdso is always installed
to /lib/modules/$(KERNELRELEASE)/vdso/.

However, modules and vdso are unrelated to each other.
kmod does not care about vdso.


The following commits started to install debug vdso.

Commit 8150caad0226 ("[POWERPC] powerpc vDSO: install unstripped
copies on disk")
Commit f79eb83b3af4 ("x86: Install unstripped copy of 64bit vdso to disk")


I do not know why they chose $(MODLIB)/vdso as the install destination.


I am thinking of split the variable into two:
MODLIB -  installation path for modules
VDSOLIB - installation path for debug vdso (not affected by kmod config)

I think that is the way to do this correctly.

Thanks

Michal

quoted

Thanks

Michal

Link: https://lore.kernel.org/linux-modules/20210112160211.5614-1-msuchanek@suse.de/ (local)

v4: set whole path to module directory instead of adding prefix
v5: use pkg-config instead of jq, fix build on openssl without sm3 support


Michal Suchanek (5):
  configure: Detect openssl sm3 support
  man/depmod.d: Fix incorrect /usr/lib search path
  libkmod, depmod: Load modprobe.d, depmod.d from ${prefix}/lib.
  kmod: Add pkgconfig file with kmod compile time configuration
  libkmod, depmod, modprobe: Make directory for kernel modules
    configurable

 Makefile.am                          |   6 +-
 configure.ac                         |  30 ++++++++
 libkmod/libkmod.c                    |  11 +--
 man/Makefile.am                      |  10 ++-
 man/depmod.d.xml                     |   9 ++-
 man/depmod.xml                       |   4 +-
 man/modinfo.xml                      |   2 +-
 man/modprobe.d.xml                   |   1 +
 man/modprobe.xml                     |   2 +-
 man/modules.dep.xml                  |   6 +-
 testsuite/module-playground/Makefile |   2 +-
 testsuite/setup-rootfs.sh            | 109 +++++++++++++++------------
 testsuite/test-depmod.c              |  16 ++--
 testsuite/test-testsuite.c           |   8 +-
 tools/depmod.c                       |   7 +-
 tools/kmod.pc.in                     |  10 +++
 tools/modinfo.c                      |   4 +-
 tools/modprobe.c                     |   4 +-
 tools/static-nodes.c                 |   6 +-
 19 files changed, 156 insertions(+), 91 deletions(-)
 create mode 100644 tools/kmod.pc.in

--
2.41.0

--
Best Regards


Masahiro Yamada