[LU-19773] DKMS: Passing $kmoddir has no effect

• Type: Improvement
• Resolution: Fixed
• Priority: Medium
• Fix Version/s: Upstream
• Severity: 3
• Assignee: Xiao Yang
• Reporter: Xiao Yang

Description

There are two issues about $kmoddir.

Issue1: DKMS cannot set $kmoddir automatically if it is not set so you need to pass the value instead.  For example, the value of kmoddir is always NULL when $kmoddir is not set and passed to DKMS.

# grep kmoddir /usr/src/lustre-client-2.17.0/dkms.conf
PRE_BUILD="lustre-dkms_pre-build.sh $module $module_version $kernelver $kernel_source_dir      $arch $source_tree $dkms_tree $kmoddir" POST_BUILD="lustre-dkms_post-build.sh $module $module_version $kernelver $kernel_source_dir      $arch $source_tree $dkms_tree $kmoddir" POST_REMOVE="lustre-dkms_post-remove.sh $module $module_version $kernelver $kernel_source_dir      $arch $source_tree $dkms_tree $kmoddir"

# head -7 config.log 
This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.
It was created by Lustre configure 2.17.0, which was
generated by GNU Autoconf 2.71.  Invocation command line was
  $ ./configure --prefix=/usr --enable-modules --disable-iokit --disable-doc --disable-utils --disable-tests --disable-maintainer-mode --with-linux=/usr/src/kernels/6.12.0-124.16.1.el10_1.x86_64 --with-linux-obj=/usr/src/kernels/6.12.0-124.16.1.el10_1.x86_64 --with-o2ib=/usr/src/ofa_kernel/default --with-kmp-moddir=/lustre-client --disable-gss --disable-server --enable-client --disable-manpages --disable-mpitests

Issue2: the value of kmoddir will be ignored even if $kmoddir is set and passed to DKMS. This behavior is defined in code and described in DKMS manpage.

code:
# grep "override_dest_module_location()$" -A 23 /usr/sbin/dkms 
override_dest_module_location()
{
    local orig_location
    orig_location="$1"
    [[ ${addon_modules_dir} ]] && echo "/${addon_modules_dir}" && return
    case "$running_distribution" in
    fedora* | rhel* | ovm*)
        echo "/extra" && return
        ;;
    sles* | suse* | opensuse*)
        echo "/updates" && return
        ;;
    debian* | ubuntu*)
        echo "/updates/dkms" && return
        ;;
    arch*)
        echo "/updates/dkms" && return
        ;;
    *)
        ;;
    esac
    echo "$orig_location"
}

DKMS manpage:
DEST_MODULE_LOCATION[#]=
       This directive specifies the destination where a module should be installed to, once compiled. It also is used for finding  original_modules.
       This  is  a  required  directive, except as noted below. This directive must start with the text "/kernel" which is in reference to /lib/mod‐
       ules/<kernelversion>/kernel.  Note that for each module within a dkms package, the numeric value of # must be the same for each of BUILT_MOD‐
       ULE_NAME , BUILT_MODULE_LOCATION , DEST_MODULE_NAME and DEST_MODULE_LOCATION and that the numbering should start at 0 (eg.  DEST_MODULE_LOCA‐
       TION[0]="/kernel/drivers/something/" DEST_MODULE_LOCATION[1]="/kernel/drivers/other/" ).
       DEST_MODULE_LOCATION is ignored on Fedora, Red Hat Enterprise Linux, SuSE Linux Enterprise Server, openSUSE and Ubuntu.  Instead, the  proper
       distribution-specific directory is used.