Kernel in the build

Commandline options

Kernel commandline options are declared using the kernel_cmdline template:


kernel_cmdline("foobar") {
  args = [ "foobar=true" ]

A single target may include multiple options:


kernel_cmdline("debug") {
  args = [

The resulting GN labels should then be inserted into the build graph via a GN argument. Note that options will be taken into account if they are within the dependency tree defined by such a GN argument.

Specifying options in board or product files

In the board or product file, add the label(s) for the desired cmdline option(s) to board_bootfs_labels and product_bootfs_labels respectively.

To alter kernel options for the zedboot or recovery build, add the labels respectively to board_zedboot_bootfs_labels and board_recovery_bootfs_labels.

Specifying options locally

For local development, a list of strings that should be appended to the kernel command line can be specified in the dev_kernel_cmdline GN variable, as follows:

fx set ... --args='dev_kernel_cmdline=["my_option=value"]'

Alternatively, an existing file can be modified by running fx args and adding or modifying a line as follows:

dev_kernel_cmdline = [

To locally alter kernel options for the zedboot or recovery build, the variables dev_zedboot_kernel_cmdline and dev_recovery_kernel_cmdline can be used, respectively.