[kmod,v5,0/5] kmod /usr support

  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.

Thanks

Michal

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

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
  

Hello,

it has been a few months since these kmod patches have been posted, and
a new kmod versio has been released since.

Is there any interest in adding this to kmod?

Thanks

Michal

On Tue, Jul 18, 2023 at 02:01:51PM +0200, Michal Suchanek wrote:
> 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.
> 
> Thanks
> 
> Michal
> 
> Link: https://lore.kernel.org/linux-modules/20210112160211.5614-1-msuchanek@suse.de/
> 
> 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
>
  

On Tue, Oct 17, 2023 at 05:45:39PM +0200, Michal Suchánek wrote:
>Hello,
>
>it has been a few months since these kmod patches have been posted, and
>a new kmod versio has been released since.
>
>Is there any interest in adding this to kmod?

yes, but I think the main drag is deciding with the kernel build system
maintainers what they are willing to accept as an interface. There isn't
much point in exporting a json config if from the kernel side they would
rather use something else. Or to use pkg-config.

I confess I lost track of that discussion. Did that settle with
pkg-config being the preferred solution?

Lucas De Marchi
  

On Tue, Oct 17, 2023 at 11:18:23AM -0500, Lucas De Marchi wrote:
> On Tue, Oct 17, 2023 at 05:45:39PM +0200, Michal Suchánek wrote:
> > Hello,
> > 
> > it has been a few months since these kmod patches have been posted, and
> > a new kmod versio has been released since.
> > 
> > Is there any interest in adding this to kmod?
> 
> yes, but I think the main drag is deciding with the kernel build system
> maintainers what they are willing to accept as an interface. There isn't
> much point in exporting a json config if from the kernel side they would
> rather use something else. Or to use pkg-config.
> 
> I confess I lost track of that discussion. Did that settle with
> pkg-config being the preferred solution?

The current discussion about the kernel side can be found here:

https://lore.kernel.org/linux-kbuild/20231017151050.GJ6241@kitsune.suse.cz/T/#t

My impression is that pkg-config is accepted as an interface on the
basis that it's already required for building the kernel while jq is
currently required only for some additional optional tools.

Thanks

Michal