ref-manual: document KERNEL_SPLIT_MODULES variable

This variable controls the kernel module spliting.

[YOCTO #15771]

(From yocto-docs rev: 198179d9c6231b5934d4fb6ede716d1dcb1442bb)

Signed-off-by: Dixit Parmar <dixitparmar19@gmail.com>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index c6ae3fb8bc..10d363a389 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -5350,6 +5350,27 @@ system and gives an overview of their function and contents.
       the :term:`KERNEL_PATH` variable. Both variables are common variables
       used by external Makefiles to point to the kernel source directory.
 
+   :term:`KERNEL_SPLIT_MODULES`
+      When inheriting the :ref:`ref-classes-kernel-module-split` class, this
+      variable controls whether kernel modules are split into separate packages
+      or bundled into a single package.
+
+      For some use cases, a monolithic kernel module package
+      :term:`KERNEL_PACKAGE_NAME` that contains all modules built from the
+      kernel sources may be preferred to speed up the installation.
+
+      By default, this variable is set to ``1``, resulting in one package per
+      module. Setting it to any other value will generate a single monolithic
+      package containing all kernel modules.
+
+      .. note::
+
+         If :term:`KERNEL_SPLIT_MODULES` is set to 0, it is still possible to
+         install all kernel modules at once by adding ``kernel-modules`` (assuming
+         :term:`KERNEL_PACKAGE_NAME` is ``kernel-modules``) to :term:`IMAGE_INSTALL`.
+         The way it works is that a placeholder "kernel-modules" package will be
+         created and will depend on every other individual kernel module packages.
+
    :term:`KERNEL_SRC`
       The location of the kernel sources. This variable is set to the value
       of the :term:`STAGING_KERNEL_DIR` within the :ref:`ref-classes-module`