On Tuesday 25 September 2012, Matthieu CASTET wrote: > > static inline char __dcc_getchar(void) > > { > > char __c; > > > > if (__LINUX_ARM_ARCH >= 6) > > asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" > > : "=r" (__c)); > > else > > asm volatile ("mrc p14, 0, %0, c1, c0 @ read comms data reg" > > : "=r" (ret)); > > isb(); > > > > return __c; > > } > > > > Arnd > > > Yes doing that will be great! > > But Alan wanted "all be runtime handled". > > May be we can do something like: > > > static int cpu_arch; > > static inline char __dcc_getchar(void) > { > char __c; > > if (cpu_arch >= 6) > asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" > : "=r" (__c)); > else > asm volatile ("mrc p14, 0, %0, c1, c0 @ read comms data reg" > : "=r" (ret)); > isb(); > > return __c; > }
It's not possible to build a kernel that runs on ARMv5 (or below) and also on ARMv6 (or above), so the effect would be exactly the same. While we are putting a lot of effort into making all sorts of ARMv6 and ARMv7 based systems work with the same kernel binary, it's highly unlikely we would ever need the above to be runtime selected, because there are a lot of other differences at assembly level. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/