Enabling MMU_MOTOROLA includes arch/m68k/kernel/ints.o in the build. arch/m68k/kernel/ints.c utilizes constants from arch/m68k/include/asm/irq.h. Some of those constants (e.g., IRQ_AUTO_1) are defined only when at least one of M680x0 (M68020, M68030, M68040, M68060) is enabled due to an if directive in arch/m68k/include/asm/irq.h. This suggests that MMU_MOTOROLA depends on M680x0. MMU_MOTOROLA is selected by a bunch of symbols; however, other than SUN3X, none of them takes M680x0 dependency into account. When MMU_MOTOROLA is enabled while none of M680x0 symbols are enabled, it results in a build error such as: arch/m68k/kernel/ints.c:61:11: error: 'IRQ_AUTO_1' undeclared (first use in this function); did you mean 'IRQ_NOAUTOEN'? 61 | for (i = IRQ_AUTO_1; i <= IRQ_AUTO_7; i++) | ^~~~~~~~~~ | IRQ_NOAUTOEN Thanks, Necip