Sometimes it may be necessary to change the default NOC-PS bootloader for some operating systems. The bootloader can be programmatically changed using a function in customconfig.php.

function nocpsforwhmcs_bootloader ($params, $osName, $profileId) {
    if ("$osName" === "...") {
        return "ipxe-1.0.0+09cc-undionly.kkpxe";
    }
}

If this function is defined in the customconfig.php file, it will be called before the installation of the operating system.
You can find a list of available bootloaders in the comments of the customconfig.php file.