The pxa-impedance-matcher is a 3rd stage loader that is used to boot legacy hardware that has a bootloader which is unable to boot DT kernels. It acts as chain loader which determines the correct hardware type and DTB blob. You should disable CONFIG_ARM_APPENDED_DTB in your kernel config. The impedance-matcher should be viewed as a replacement for that option. It used to be completetly specific to PXA3xx based Raumfeld hardware, but was turned into a more generic kind of framework recently. WARNING: PLEASE ONLY USE THIS TOOL AS A LAST RESORT OPTION FOR LEGACY HARDWARE, AND NOT AS AN OPTION FOR NEW DEVELOPMENTS. THE CLEARLY ADVISED WAY IS TO ADD PROPER DTB SUPPORT TO YOUR BOOTLOADER.