Same thoughts here. You'd have to define DMB in _atomic_lock.c as you did for cpufunc_asm_armv7.S and use that.
Also, I think it's the old binutils 2.15/as, not gcc. Am 01.08.2013 um 04:56 schrieb Artturi Alm <artturi....@gmail.com>: > Like i wrote earlier, i don't think it's supported, because of > -march=armv6 and gcc version 4.2.1 20070719, unless i have missed > something. > > On 08/01/13 02:28, Richard Allen wrote: >> Could we just use GCC intrinsics in C? >> On Jul 31, 2013 9:08 AM, "Artturi Alm" <artturi....@gmail.com> wrote: >> >>> On 07/31/13 16:37, Artturi Alm wrote: >>> >>>> On 07/31/13 08:57, Richard Allen wrote: >>>> >>>>> Hi, >>>>> >>>>> I just wanted to let you know that _atomic_lock(), from _atomic_lock.c, >>>>> as used by librthread should probably have a barrier instruction added >>>>> to prevent the processor from reordering loads/stores around the >>>>> atomic_lock. >>>>> >>>>> For more information about barriers on ARM, see: >>>>> http://infocenter.arm.com/**help/index.jsp?topic=/com.arm.** >>>>> doc.dui0489c/CIHGHHIE.html<http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0489c/CIHGHHIE.html> >>>>> >>>>> >>>>> For some examples, see sections 7.2.1 and 7.2.2 >>>>> http://infocenter.arm.com/**help/topic/com.arm.doc.** >>>>> genc007826/Barrier_Litmus_**Tests_and_Cookbook_A08.pdf<http://infocenter.arm.com/help/topic/com.arm.doc.genc007826/Barrier_Litmus_Tests_and_Cookbook_A08.pdf> >>>>> >>>>> >>>>> -Richard >>>>> >>>>> >>>> Hi, >>>> >>>> I'm not sure what the diff against _atomic_lock.c would look like, >>>> since i'm guessing it might not be supported, and i don't like >>>> inline asm so i'll leave it to someone else, however, diff for >>>> using it in cpufunc_asm_armv7.S would be something like below >>>> >>>> >>> Wow, that was unclear. what i meant with 'it' was of course the dmb >>> instruction, and fwiw freebsd uses it exclusively in atomic.h inlines. >>> >>> >>>> -Artturi >>>> >>>> >>>> >>>> Index: cpufunc_asm_armv7.S >>>> ==============================**==============================**======= >>>> RCS file: /cvs/src/sys/arch/arm/arm/**cpufunc_asm_armv7.S,v >>>> retrieving revision 1.6 >>>> diff -u -p -r1.6 cpufunc_asm_armv7.S >>>> --- cpufunc_asm_armv7.S 30 Mar 2013 01:30:30 -0000 1.6 >>>> +++ cpufunc_asm_armv7.S 31 Jul 2013 13:26:18 -0000 >>>> @@ -19,6 +19,7 @@ >>>> #include <machine/asm.h> >>>> >>>> #define DSB .long 0xf57ff040 >>>> +#define DMB .long 0xf57ff050 >>>> #define ISB .long 0xf57ff060 >>>> #define WFI .long 0xe320f003
