On 08/08/13 08:20, zhaobin xv wrote: > Hi > > In linux/arch/arm/boot/ > compressed/head.S: > > > #ifndef __ARM_ARCH_2__ > /* > * Booting from Angel - need to enter SVC mode and disable > * FIQs/IRQs (numeric definitions from angel arm.h source). > * We only do this if we were in user mode on entry. > */ > mrs r2, cpsr @ get current mode > tst r2, #3 @ not user? > bne not_angel > mov r0, #0x17 @ angel_SWIreason_EnterSVC > swi 0x123456 @ angel_SWI_ARM > > > I don't know what the"__ARM_ARCH_2__" mean? > "__ARM_ARCH_2__" is definded by gcc or definded byarmlinux? > where does it come from? what does it want to do? > > >
__ARM_ARCH_2__ is defined by GCC when compiling for an ARM cpu that implements the ARMv2 revision of the architecture. ARMv2 is now obsolete and you'll almost certainly not want to support that now. R.
