HelenOS sources

ID_PFR0_ARM_MASK  142 boot/arch/arm32/include/arch/cp15.h 	ID_PFR0_ARM_MASK = 0xf << 0,
ID_PFR0_ARM_MASK  142 kernel/arch/arm32/include/arch/cp15.h 	ID_PFR0_ARM_MASK = 0xf << 0,
ID_PFR0_ARM_MASK  142 uspace/lib/c/arch/arm32/include/libarch/cp15.h 	ID_PFR0_ARM_MASK = 0xf << 0,
HelenOS homepage, sources at GitHub