On Skylake with no verstage and FSP 1.1 there is no car_stage_entry function, only a weak symbol with an infinite loop in src/arch/x86/assembly_entry.S, and as a result coreboot hangs after jumping into the romstage.
There is one defined in src/soc/intel/skylake/romstage/car_stage.S, but this is only linked if FSP 2.0 is used. The Chell chromebook appears to use FSP 1.1, so I don't have the FSP-S and FSP-M binaries.
Does the car stage code exist somewhere else in the tree?