This topic provides details about Legato's Kernel Module Definition file.

The .mdef files support declaring pre-built kernel modules to use Legato.

.mdef files contain the following sections:

preBuilt

The mandatory preBuilt: section specifies the path to the pre-built kernel module binary file. This binary file will be bundled with Legato and installed on the target using insmod Linux command.

The module binary file specified must have an extension .ko to indicate the kernel module binary.

This code sample shows how the kernel module binary file /path/to/module/hello.ko is bundled with Legato:

{
    preBuilt: /path/to/kernel/module/hello.ko
}

params

The optional params: section lists all module parameters that must be provided to the module’s insmod command.

The following code sample will execute this command insmod <module> param1=value1 param2=value2 …:

params:
{
    param1 = “value1”
    param2 = “value2”
    …
}

The mandatory quotes (“ ”) around each parameter value indicate a string type.

Build Kernel Modules

For info on how to build Linux kernel modules, see the Yocto kernel dev docs and

$(KERNEL_SRC)/Documentation/kbuild/modules.txt file

Build Directory

Kernel module binares are built in the Yocto Linux kernel build environment, preferably with Yocto cross-build tools.

Modules have to be built from the Yocto kernel’s build directory.

From the Yocto tree root, this is the path to kernel build directory:

<Yocto-root>/build_bin/tmp/work/swi_mdm9x15-poky-linux-gnueabi/linux-yocto/<kernel-version>/linux-swi_mdm9x15-standard-build

From the Legato directory, this is the path to kernel build directory:

../build_bin/tmp/work/swi_mdm9x15-poky-linux-gnueabi/linux-yocto/<kernel-version>/linux-swi_mdm9x15-standard-build

Kernel Driver

See Out-of-Tree Kernel Modules for details.

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