[PATCH v3 0/1] Add support to build binary version of DKMS kernel modules

[PATCH v3 0/1] Add support to build binary version of DKMS kernel modules

[Felix Moessbauer]

Hi,

this also fixes the build for i386.

Changes since v3:

- ensure that the module is build before packaging (fixes i386)
- add mapping between ISAR arch name and kernel (machine) arch 

Best regards,
Felix

Felix Moessbauer (1):
  Add support to build binary version of DKMS kernel modules

 meta-isar/conf/local.conf.sample              |  5 +-
 .../example-dkms-module.bb                    | 14 ++++
 meta/classes/dkms-module.bbclass              | 76 +++++++++++++++++++
 scripts/ci_build.sh                           |  1 +
 4 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
 create mode 100644 meta/classes/dkms-module.bbclass

-- 
2.20.1

[PATCH v3 1/1] Add support to build binary version of DKMS kernel modules

[Felix Moessbauer]

This patch adds support to build and install a kernel module that is available
via a debian DKMS package.
As it is hard to directly build and install the package we create and distribute
a meta package that is independent of the kernel version.
In that package, we depend on the versioned prebuild kernel module package.

To build the dkms module, we add two tasks and directly
use dkms to build the debian package containing the binary module
Then we just copy the binary-module debian package to the workdir,

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta-isar/conf/local.conf.sample              |  5 +-
 .../example-dkms-module.bb                    | 14 ++++
 meta/classes/dkms-module.bbclass              | 76 +++++++++++++++++++
 scripts/ci_build.sh                           |  1 +
 4 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
 create mode 100644 meta/classes/dkms-module.bbclass

diff --git a/meta-isar/conf/local.conf.sample b/meta-isar/conf/local.conf.sample
index 77585ec..67a98d6 100644
--- a/meta-isar/conf/local.conf.sample
+++ b/meta-isar/conf/local.conf.sample
@@ -178,7 +178,10 @@ CONF_VERSION = "1"
 
 #
 # The default list of extra packages to be installed.
-IMAGE_INSTALL = "hello-isar example-raw example-module-${KERNEL_NAME} enable-fsck isar-exclude-docs samefile hello isar-disable-apt-cache cowsay example-prebuilt"
+IMAGE_INSTALL = "hello-isar example-raw example-module-${KERNEL_NAME} example-dkms-module-${KERNEL_NAME} enable-fsck isar-exclude-docs samefile hello isar-disable-apt-cache cowsay example-prebuilt"
+
+# v4l2loopback module does not build on armhf
+IMAGE_INSTALL_remove_armhf = "example-dkms-module-${KERNEL_NAME}"
 
 #
 # Enable cross-compilation support
diff --git a/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb b/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
new file mode 100644
index 0000000..113f232
--- /dev/null
+++ b/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
@@ -0,0 +1,14 @@
+# Example recipe for building the binary version of a DKMS module
+#
+# This software is a part of ISAR.
+# Copyright (c) Siemens AG, 2021
+#
+# SPDX-License-Identifier: MIT
+
+inherit dkms-module
+
+PN .= "-${KERNEL_NAME}"
+
+#package name (without -dkms. E.g "v4l2loopback" for package "v4l2loopback-dkms")
+DKMS_PACKAGE_NAME = "v4l2loopback"
+AUTOLOAD += "v4l2loopback"
diff --git a/meta/classes/dkms-module.bbclass b/meta/classes/dkms-module.bbclass
new file mode 100644
index 0000000..283bff7
--- /dev/null
+++ b/meta/classes/dkms-module.bbclass
@@ -0,0 +1,76 @@
+# This software is a part of ISAR.
+# Copyright (C) 2021 Siemens AG
+#
+# SPDX-License-Identifier: MIT
+
+inherit dpkg-raw
+
+# Build and install a kernel module that is available via a debian DKMS package.
+# As it is hard to directly build and install the package we create and distribute
+# a meta package that is independent of the kernel version.
+# In that package, we depend on the versioned prebuild kernel module package.
+#
+# To build the dkms module, we add two tasks and directly
+# use dkms to build the debian package containing the binary module
+# Then we just copy the binary-module debian package to the workdir,
+# so ISAR's do_deploy_deb picks it up.
+
+#package name (without -dkms. E.g "dpdk-kmods" for package "dpdk-kmods-dkms")
+DKMS_PACKAGE_NAME ?= ""
+AUTOLOAD ?= ""
+
+DESCRIPTION ?= "Kernel module from DKMS package for ${PN}"
+DEPENDS += "linux-headers-${KERNEL_NAME}"
+DEBIAN_DEPENDS += "${DKMS_PACKAGE_NAME}-modules,"
+DEBIAN_BUILD_DEPENDS += "linux-headers-${KERNEL_NAME}, ${DKMS_PACKAGE_NAME}-dkms,"
+
+ISAR_CROSS_COMPILE = "0"
+
+# install configuration to auto-load the modules in ${AUTOLOAD}
+do_install() {
+    # auto load the module
+    install -v -d ${D}/etc/modules-load.d
+    for module in "${AUTOLOAD}"; do
+        echo $module > ${D}/etc/modules-load.d/${PN}.conf
+    done
+}
+
+# build the binary kernel module and package as debian package (versioned)
+do_module_build() {
+    # we have to find out the module version, e.g. dpdk-kmods/0~20201113+git -k 5.10.0-3-rt-amd64/x86_64
+    REVISION=$(find ${BUILDCHROOT_DIR}/usr/src/${DKMS_PACKAGE_NAME}-* -type d -exec basename {} + | sed 's/${DKMS_PACKAGE_NAME}-//g')
+    DKMS_ARCH=$(echo ${DISTRO_ARCH} | sed 's/amd64/x86_64/g' | sed 's/arm64/aarch64/g' | sed 's/i386/i686/g')
+    if ! dpkg -s --root=${BUILDCHROOT_DIR} linux-headers-${KERNEL_NAME} | grep "Depends:.*linux-headers"; then
+        # custom kernels directly place their files in linux-image-KERNEL-NAME, instead
+        # of using a meta package + a versioned package with the resources
+        # The prebuild DKMS binary package depends on the versioned kernel package,
+        # but that is not available on custom kernels. Hence, we just remove the dependency.
+        bbnote "Building ${DKMS_PACKAGE_NAME} for custom kernel ${KERNEL_NAME}"
+        cp ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control ${WORKDIR}/control.dkms.orig
+        sudo sed -i 's/, linux-image-KERNEL_VERSION//' ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control
+	KERNEL_FULLNAME=${KERNEL_NAME}
+    else
+	KERNEL_FULLNAME=$(dpkg -s --root=${BUILDCHROOT_DIR} linux-headers-${KERNEL_NAME} | grep "Depends:.*linux-headers" | sed 's/Depends: linux-headers-//g')
+	bbnote "Building for kernel $KERNEL_FULLNAME"
+    fi
+    # build the module for all installed kernels (should be just one)
+    sudo -E chroot ${BUILDCHROOT_DIR} dkms build ${DKMS_PACKAGE_NAME}/${REVISION} -k ${KERNEL_FULLNAME}/${DKMS_ARCH}
+    sudo -E chroot ${BUILDCHROOT_DIR} dkms mkbmdeb ${DKMS_PACKAGE_NAME}/${REVISION} -k ${KERNEL_FULLNAME}/${DKMS_ARCH}
+    DKMS_PACKAGE_VERSIONED=$(find ${BUILDCHROOT_DIR}/var/lib/dkms/${DKMS_PACKAGE_NAME}/ -name "${DKMS_PACKAGE_NAME}-modules*.deb" -exec dpkg -I {} + | grep "Package:" | awk '{print $2}')
+    if [ -z "$DKMS_PACKAGE_VERSIONED" ]; then
+        bberror "No prebuild dkms module found"
+        exit 1
+    fi
+    # restore dkms template (if any)
+    cp ${WORKDIR}/control.dkms.orig ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control || true
+}
+
+# simply copy our module from the build tree to the expected output location
+# of this recipe. Then, do_deploy_dep finds it and adds it to the
+# debian isar repo
+do_module_deploy() {
+    cp ${BUILDCHROOT_DIR}/var/lib/dkms/${DKMS_PACKAGE_NAME}/*/bmdeb/*.deb ${S}/../
+}
+
+addtask module_build after do_install_builddeps before do_dpkg_build
+addtask module_deploy after do_module_build before do_deploy_deb
diff --git a/scripts/ci_build.sh b/scripts/ci_build.sh
index adc22e4..1426569 100755
--- a/scripts/ci_build.sh
+++ b/scripts/ci_build.sh
@@ -259,6 +259,7 @@ mv ${BUILDDIR}/tmp/deploy/images/qemuamd64/isar-image-base-debian-stretch-qemuam
 
 # Finalize with containerized images, since they remove some not-needed packages from the local.conf
 sed -i -e 's/\(IMAGE_INSTALL = .*\) example-module-${KERNEL_NAME}\(.*\)/\1\2/g' conf/local.conf
+sed -i -e 's/\(IMAGE_INSTALL = .*\) example-dkms-module-${KERNEL_NAME}\(.*\)/\1\2/g' conf/local.conf
 sed -i -e 's/\(IMAGE_INSTALL = .*\) enable-fsck\(.*\)/\1\2/g' conf/local.conf
 bitbake $BB_ARGS $TARGETS_CONTAINERS
 while [ -e bitbake.sock ]; do sleep 1; done
-- 
2.20.1

Re: [PATCH v3 0/1] Add support to build binary version of DKMS kernel modules

[Anton Mikanovich]

Please pay more attention to patchset versioning next time. You've 
already sent v3, so this one supposed to be PATCH v4.
Also make sure the header of the cover letter to be the same as separate 
patches have, linux-perf series has an issues with that.
Thank you.

30.04.2021 17:02, Felix Moessbauer write:
> Hi,
>
> this also fixes the build for i386.
>
> Changes since v3:
>
> - ensure that the module is build before packaging (fixes i386)
> - add mapping between ISAR arch name and kernel (machine) arch
>
> Best regards,
> Felix
>
> Felix Moessbauer (1):
>    Add support to build binary version of DKMS kernel modules
>
>   meta-isar/conf/local.conf.sample              |  5 +-
>   .../example-dkms-module.bb                    | 14 ++++
>   meta/classes/dkms-module.bbclass              | 76 +++++++++++++++++++
>   scripts/ci_build.sh                           |  1 +
>   4 files changed, 95 insertions(+), 1 deletion(-)
>   create mode 100644 meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
>   create mode 100644 meta/classes/dkms-module.bbclass
>
-- 
Anton Mikanovich
Promwad Ltd.
External service provider of ilbers GmbH
Maria-Merian-Str. 8
85521 Ottobrunn, Germany
+49 (89) 122 67 24-0
Commercial register Munich, HRB 214197
General Manager: Baurzhan Ismagulov

Re: [PATCH v3 1/1] Add support to build binary version of DKMS kernel modules

[Henning Schild]

Hi Felix,

one generic question ... does this potentially also have sort of a
"apt-get update" problem?

Say we build with isar and deploy a package feed to our target, would
that target be able to update its kernel and the package ... having
both module versions installed and working depending which kernel is
booted?

Am Fri, 30 Apr 2021 16:02:52 +0200
schrieb Felix Moessbauer <felix.moessbauer@siemens.com>:

> This patch adds support to build and install a kernel module that is
> available via a debian DKMS package.
> As it is hard to directly build and install the package we create and
> distribute a meta package that is independent of the kernel version.
> In that package, we depend on the versioned prebuild kernel module
> package.
> 
> To build the dkms module, we add two tasks and directly
> use dkms to build the debian package containing the binary module
> Then we just copy the binary-module debian package to the workdir,
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
>  meta-isar/conf/local.conf.sample              |  5 +-
>  .../example-dkms-module.bb                    | 14 ++++
>  meta/classes/dkms-module.bbclass              | 76
> +++++++++++++++++++ scripts/ci_build.sh                           |
> 1 + 4 files changed, 95 insertions(+), 1 deletion(-)
>  create mode 100644
> meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
> create mode 100644 meta/classes/dkms-module.bbclass
> 
> diff --git a/meta-isar/conf/local.conf.sample
> b/meta-isar/conf/local.conf.sample index 77585ec..67a98d6 100644
> --- a/meta-isar/conf/local.conf.sample
> +++ b/meta-isar/conf/local.conf.sample
> @@ -178,7 +178,10 @@ CONF_VERSION = "1"
>  
>  #
>  # The default list of extra packages to be installed.
> -IMAGE_INSTALL = "hello-isar example-raw
> example-module-${KERNEL_NAME} enable-fsck isar-exclude-docs samefile
> hello isar-disable-apt-cache cowsay example-prebuilt" +IMAGE_INSTALL
> = "hello-isar example-raw example-module-${KERNEL_NAME}
> example-dkms-module-${KERNEL_NAME} enable-fsck isar-exclude-docs
> samefile hello isar-disable-apt-cache cowsay example-prebuilt" + +#
> v4l2loopback module does not build on armhf
> +IMAGE_INSTALL_remove_armhf = "example-dkms-module-${KERNEL_NAME}" #
> # Enable cross-compilation support diff --git
> a/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
> b/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
> new file mode 100644 index 0000000..113f232 --- /dev/null
> +++
> b/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
> @@ -0,0 +1,14 @@ +# Example recipe for building the binary version of
> a DKMS module +#
> +# This software is a part of ISAR.
> +# Copyright (c) Siemens AG, 2021
> +#
> +# SPDX-License-Identifier: MIT
> +
> +inherit dkms-module
> +
> +PN .= "-${KERNEL_NAME}"
> +
> +#package name (without -dkms. E.g "v4l2loopback" for package
> "v4l2loopback-dkms") +DKMS_PACKAGE_NAME = "v4l2loopback"
> +AUTOLOAD += "v4l2loopback"
> diff --git a/meta/classes/dkms-module.bbclass
> b/meta/classes/dkms-module.bbclass new file mode 100644
> index 0000000..283bff7
> --- /dev/null
> +++ b/meta/classes/dkms-module.bbclass
> @@ -0,0 +1,76 @@
> +# This software is a part of ISAR.
> +# Copyright (C) 2021 Siemens AG
> +#
> +# SPDX-License-Identifier: MIT
> +
> +inherit dpkg-raw
> +
> +# Build and install a kernel module that is available via a debian
> DKMS package. +# As it is hard to directly build and install the
> package we create and distribute +# a meta package that is
> independent of the kernel version. +# In that package, we depend on
> the versioned prebuild kernel module package. +#
> +# To build the dkms module, we add two tasks and directly
> +# use dkms to build the debian package containing the binary module
> +# Then we just copy the binary-module debian package to the workdir,
> +# so ISAR's do_deploy_deb picks it up.
> +
> +#package name (without -dkms. E.g "dpdk-kmods" for package
> "dpdk-kmods-dkms") +DKMS_PACKAGE_NAME ?= ""
> +AUTOLOAD ?= ""
> +
> +DESCRIPTION ?= "Kernel module from DKMS package for ${PN}"
> +DEPENDS += "linux-headers-${KERNEL_NAME}"
> +DEBIAN_DEPENDS += "${DKMS_PACKAGE_NAME}-modules,"
> +DEBIAN_BUILD_DEPENDS += "linux-headers-${KERNEL_NAME},

why do those three to += ? i would imagine a recipe using += or a class
using ?=

> ${DKMS_PACKAGE_NAME}-dkms," +
> +ISAR_CROSS_COMPILE = "0"
> +
> +# install configuration to auto-load the modules in ${AUTOLOAD}
> +do_install() {
> +    # auto load the module
> +    install -v -d ${D}/etc/modules-load.d
> +    for module in "${AUTOLOAD}"; do
> +        echo $module > ${D}/etc/modules-load.d/${PN}.conf
> +    done
> +}
> +
> +# build the binary kernel module and package as debian package
> (versioned) +do_module_build() {
> +    # we have to find out the module version, e.g.
> dpdk-kmods/0~20201113+git -k 5.10.0-3-rt-amd64/x86_64

switch comment to v4l?

> +    REVISION=$(find
> ${BUILDCHROOT_DIR}/usr/src/${DKMS_PACKAGE_NAME}-* -type d -exec
> basename {} + | sed 's/${DKMS_PACKAGE_NAME}-//g')
> +    DKMS_ARCH=$(echo ${DISTRO_ARCH} | sed 's/amd64/x86_64/g' | sed
> 's/arm64/aarch64/g' | sed 's/i386/i686/g')
> +    if ! dpkg -s --root=${BUILDCHROOT_DIR}
> linux-headers-${KERNEL_NAME} | grep "Depends:.*linux-headers"; then

can be convice that first command to use a format we do not need to
parse with grep?
Along the lines of "dpkg-deb --show --showformat '${Version}'"

> +        # custom kernels directly place their files in
> linux-image-KERNEL-NAME, instead
> +        # of using a meta package + a versioned package with the
> resources
> +        # The prebuild DKMS binary package depends on the versioned
> kernel package,
> +        # but that is not available on custom kernels. Hence, we
> just remove the dependency.
> +        bbnote "Building ${DKMS_PACKAGE_NAME} for custom kernel
> ${KERNEL_NAME}"
> +        cp
> ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control
> ${WORKDIR}/control.dkms.orig

good idea to keep that backup, but i guess if we run this task twice
because it failed inbetween, that might not work

usual solutions are "rm -rf" or [cleandirs] ... maybe that is in here
but i did not see it

Henning

> +        sudo sed -i 's/, linux-image-KERNEL_VERSION//'
> ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control
> +	KERNEL_FULLNAME=${KERNEL_NAME}
> +    else
> +	KERNEL_FULLNAME=$(dpkg -s --root=${BUILDCHROOT_DIR}
> linux-headers-${KERNEL_NAME} | grep "Depends:.*linux-headers" | sed
> 's/Depends: linux-headers-//g')
> +	bbnote "Building for kernel $KERNEL_FULLNAME"
> +    fi
> +    # build the module for all installed kernels (should be just one)
> +    sudo -E chroot ${BUILDCHROOT_DIR} dkms build
> ${DKMS_PACKAGE_NAME}/${REVISION} -k ${KERNEL_FULLNAME}/${DKMS_ARCH}
> +    sudo -E chroot ${BUILDCHROOT_DIR} dkms mkbmdeb
> ${DKMS_PACKAGE_NAME}/${REVISION} -k ${KERNEL_FULLNAME}/${DKMS_ARCH}
> +    DKMS_PACKAGE_VERSIONED=$(find
> ${BUILDCHROOT_DIR}/var/lib/dkms/${DKMS_PACKAGE_NAME}/ -name
> "${DKMS_PACKAGE_NAME}-modules*.deb" -exec dpkg -I {} + | grep
> "Package:" | awk '{print $2}')
> +    if [ -z "$DKMS_PACKAGE_VERSIONED" ]; then
> +        bberror "No prebuild dkms module found"
> +        exit 1
> +    fi
> +    # restore dkms template (if any)
> +    cp ${WORKDIR}/control.dkms.orig
> ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control ||
> true +} +
> +# simply copy our module from the build tree to the expected output
> location +# of this recipe. Then, do_deploy_dep finds it and adds it
> to the +# debian isar repo
> +do_module_deploy() {
> +    cp
> ${BUILDCHROOT_DIR}/var/lib/dkms/${DKMS_PACKAGE_NAME}/*/bmdeb/*.deb
> ${S}/../ +} +
> +addtask module_build after do_install_builddeps before do_dpkg_build
> +addtask module_deploy after do_module_build before do_deploy_deb
> diff --git a/scripts/ci_build.sh b/scripts/ci_build.sh
> index adc22e4..1426569 100755
> --- a/scripts/ci_build.sh
> +++ b/scripts/ci_build.sh
> @@ -259,6 +259,7 @@ mv
> ${BUILDDIR}/tmp/deploy/images/qemuamd64/isar-image-base-debian-stretch-qemuam 
>  # Finalize with containerized images, since they remove some
> not-needed packages from the local.conf sed -i -e 's/\(IMAGE_INSTALL
> = .*\) example-module-${KERNEL_NAME}\(.*\)/\1\2/g' conf/local.conf
> +sed -i -e 's/\(IMAGE_INSTALL = .*\)
> example-dkms-module-${KERNEL_NAME}\(.*\)/\1\2/g' conf/local.conf sed
> -i -e 's/\(IMAGE_INSTALL = .*\) enable-fsck\(.*\)/\1\2/g'
> conf/local.conf bitbake $BB_ARGS $TARGETS_CONTAINERS while [ -e
> bitbake.sock ]; do sleep 1; done

Re: [PATCH v3 1/1] Add support to build binary version of DKMS kernel modules

[Anton Mikanovich]

26.04.2021 19:16, Felix Moessbauer wrote:
> This patch adds support to build and install a kernel module that is available
> via a debian DKMS package.
> As it is hard to directly build and install the package we create and distribute
> a meta package that is independent of the kernel version.
> In that package, we depend on the versioned prebuild kernel module package.
>
> To build the dkms module, we add two tasks and directly
> use dkms to build the debian package containing the binary module
> Then we just copy the binary-module debian package to the workdir,
>
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>

There is an issue on building example-dkms-module-686-pae for 
mc:qemui386-stretch:isar-image-base target in case of ISAR_CROSS_COMPILE 
is set to 0:
 >Gathering binaries...Error! No modules built for 4.9.0-15-686-pae (i386).
Please try and fix.

-- 
Anton Mikanovich
Promwad Ltd.
External service provider of ilbers GmbH
Maria-Merian-Str. 8
85521 Ottobrunn, Germany
+49 (89) 122 67 24-0
Commercial register Munich, HRB 214197
General Manager: Baurzhan Ismagulov

[PATCH v3 1/1] Add support to build binary version of DKMS kernel modules

[Felix Moessbauer]

This patch adds support to build and install a kernel module that is available
via a debian DKMS package.
As it is hard to directly build and install the package we create and distribute
a meta package that is independent of the kernel version.
In that package, we depend on the versioned prebuild kernel module package.

To build the dkms module, we add two tasks and directly
use dkms to build the debian package containing the binary module
Then we just copy the binary-module debian package to the workdir,

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta-isar/conf/local.conf.sample              |  5 +-
 .../example-dkms-module.bb                    | 14 ++++
 meta/classes/dkms-module.bbclass              | 75 +++++++++++++++++++
 scripts/ci_build.sh                           |  1 +
 4 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
 create mode 100644 meta/classes/dkms-module.bbclass

diff --git a/meta-isar/conf/local.conf.sample b/meta-isar/conf/local.conf.sample
index 77585ec..67a98d6 100644
--- a/meta-isar/conf/local.conf.sample
+++ b/meta-isar/conf/local.conf.sample
@@ -178,7 +178,10 @@ CONF_VERSION = "1"
 
 #
 # The default list of extra packages to be installed.
-IMAGE_INSTALL = "hello-isar example-raw example-module-${KERNEL_NAME} enable-fsck isar-exclude-docs samefile hello isar-disable-apt-cache cowsay example-prebuilt"
+IMAGE_INSTALL = "hello-isar example-raw example-module-${KERNEL_NAME} example-dkms-module-${KERNEL_NAME} enable-fsck isar-exclude-docs samefile hello isar-disable-apt-cache cowsay example-prebuilt"
+
+# v4l2loopback module does not build on armhf
+IMAGE_INSTALL_remove_armhf = "example-dkms-module-${KERNEL_NAME}"
 
 #
 # Enable cross-compilation support
diff --git a/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb b/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
new file mode 100644
index 0000000..113f232
--- /dev/null
+++ b/meta-isar/recipes-kernel/example-dkms-module/example-dkms-module.bb
@@ -0,0 +1,14 @@
+# Example recipe for building the binary version of a DKMS module
+#
+# This software is a part of ISAR.
+# Copyright (c) Siemens AG, 2021
+#
+# SPDX-License-Identifier: MIT
+
+inherit dkms-module
+
+PN .= "-${KERNEL_NAME}"
+
+#package name (without -dkms. E.g "v4l2loopback" for package "v4l2loopback-dkms")
+DKMS_PACKAGE_NAME = "v4l2loopback"
+AUTOLOAD += "v4l2loopback"
diff --git a/meta/classes/dkms-module.bbclass b/meta/classes/dkms-module.bbclass
new file mode 100644
index 0000000..f656f07
--- /dev/null
+++ b/meta/classes/dkms-module.bbclass
@@ -0,0 +1,75 @@
+# This software is a part of ISAR.
+# Copyright (C) 2021 Siemens AG
+#
+# SPDX-License-Identifier: MIT
+
+inherit dpkg-raw
+
+# Build and install a kernel module that is available via a debian DKMS package.
+# As it is hard to directly build and install the package we create and distribute
+# a meta package that is independent of the kernel version.
+# In that package, we depend on the versioned prebuild kernel module package.
+#
+# To build the dkms module, we add two tasks and directly
+# use dkms to build the debian package containing the binary module
+# Then we just copy the binary-module debian package to the workdir,
+# so ISAR's do_deploy_deb picks it up.
+
+#package name (without -dkms. E.g "dpdk-kmods" for package "dpdk-kmods-dkms")
+DKMS_PACKAGE_NAME ?= ""
+AUTOLOAD ?= ""
+
+DESCRIPTION ?= "Kernel module from DKMS package for ${PN}"
+DEPENDS += "linux-headers-${KERNEL_NAME}"
+DEBIAN_DEPENDS += "${DKMS_PACKAGE_NAME}-modules,"
+DEBIAN_BUILD_DEPENDS += "linux-headers-${KERNEL_NAME}, ${DKMS_PACKAGE_NAME}-dkms,"
+
+ISAR_CROSS_COMPILE = "0"
+
+# install configuration to auto-load the modules in ${AUTOLOAD}
+do_install() {
+    # auto load the module
+    install -v -d ${D}/etc/modules-load.d
+    for module in "${AUTOLOAD}"; do
+        echo $module > ${D}/etc/modules-load.d/${PN}.conf
+    done
+}
+
+# build the binary kernel module and package as debian package (versioned)
+do_module_build() {
+    # we have to find out the module version, e.g. dpdk-kmods/0~20201113+git -k 5.10.0-3-rt-amd64/x86_64
+    REVISION=$(find ${BUILDCHROOT_DIR}/usr/src/${DKMS_PACKAGE_NAME}-* -type d -exec basename {} + | sed 's/${DKMS_PACKAGE_NAME}-//g')
+    DKMS_ARCH=$(echo ${DISTRO_ARCH} | sed 's/amd64/x86_64/g' | sed 's/arm64/aarch64/g')
+    if ! dpkg -s --root=${BUILDCHROOT_DIR} linux-headers-${KERNEL_NAME} | grep "Depends:.*linux-headers"; then
+        # custom kernels directly place their files in linux-image-KERNEL-NAME, instead
+        # of using a meta package + a versioned package with the resources
+        # The prebuild DKMS binary package depends on the versioned kernel package,
+        # but that is not available on custom kernels. Hence, we just remove the dependency.
+        bbnote "Building ${DKMS_PACKAGE_NAME} for custom kernel ${KERNEL_NAME}"
+        cp ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control ${WORKDIR}/control.dkms.orig
+        sudo sed -i 's/, linux-image-KERNEL_VERSION//' ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control
+	KERNEL_FULLNAME=${KERNEL_NAME}
+    else
+	KERNEL_FULLNAME=$(dpkg -s --root=${BUILDCHROOT_DIR} linux-headers-${KERNEL_NAME} | grep "Depends:.*linux-headers" | sed 's/Depends: linux-headers-//g')
+	bbnote "Building for kernel $KERNEL_FULLNAME"
+    fi
+    # build the module for all installed kernels (should be just one)
+    sudo -E chroot ${BUILDCHROOT_DIR} dkms mkbmdeb ${DKMS_PACKAGE_NAME}/${REVISION} -k ${KERNEL_FULLNAME}/${DKMS_ARCH}
+    DKMS_PACKAGE_VERSIONED=$(find ${BUILDCHROOT_DIR}/var/lib/dkms/${DKMS_PACKAGE_NAME}/ -name "${DKMS_PACKAGE_NAME}-modules*.deb" -exec dpkg -I {} + | grep "Package:" | awk '{print $2}')
+    if [ -z "$DKMS_PACKAGE_VERSIONED" ]; then
+        bberror "No prebuild dkms module found"
+        exit 1
+    fi
+    # restore dkms template (if any)
+    cp ${WORKDIR}/control.dkms.orig ${BUILDCHROOT_DIR}/etc/dkms/template-dkms-mkbmdeb/debian/control || true
+}
+
+# simply copy our module from the build tree to the expected output location
+# of this recipe. Then, do_deploy_dep finds it and adds it to the
+# debian isar repo
+do_module_deploy() {
+    cp ${BUILDCHROOT_DIR}/var/lib/dkms/${DKMS_PACKAGE_NAME}/*/bmdeb/*.deb ${S}/../
+}
+
+addtask module_build after do_install_builddeps before do_dpkg_build
+addtask module_deploy after do_module_build before do_deploy_deb
diff --git a/scripts/ci_build.sh b/scripts/ci_build.sh
index adc22e4..1426569 100755
--- a/scripts/ci_build.sh
+++ b/scripts/ci_build.sh
@@ -259,6 +259,7 @@ mv ${BUILDDIR}/tmp/deploy/images/qemuamd64/isar-image-base-debian-stretch-qemuam
 
 # Finalize with containerized images, since they remove some not-needed packages from the local.conf
 sed -i -e 's/\(IMAGE_INSTALL = .*\) example-module-${KERNEL_NAME}\(.*\)/\1\2/g' conf/local.conf
+sed -i -e 's/\(IMAGE_INSTALL = .*\) example-dkms-module-${KERNEL_NAME}\(.*\)/\1\2/g' conf/local.conf
 sed -i -e 's/\(IMAGE_INSTALL = .*\) enable-fsck\(.*\)/\1\2/g' conf/local.conf
 bitbake $BB_ARGS $TARGETS_CONTAINERS
 while [ -e bitbake.sock ]; do sleep 1; done
-- 
2.20.1