On Wed, Nov 18, 2009 at 06:34:00PM +0100, Martin Schwidefsky wrote: > used for parameter passing. 64 bit values are passed as registers pairs > with the first register an even numbered register. The effect of that > rule is that parameter registers may be skipped or that the whole 64 bit > value is passed on the stack. Examples: Erm, did I miss something? The 32 bit ABI doesn't say anything about even/odd register pairs for 64 bit values. Also gcc doesn't generate such code: > fn(int a, long long b, int c) > a is passed in %r2, b is passed in %r4/%r5, c is passed in %r6, %r3 is > skipped. extern void fn(int a, long long b, int c); void bla(void) { fn(0, 1, 2); } 00000000 <bla>: 0: 90 ef f0 38 stm %r14,%r15,56(%r15) 4: a7 fa ff a0 ahi %r15,-96 8: a7 28 00 00 lhi %r2,0 c: a7 38 00 00 lhi %r3,0 10: a7 48 00 01 lhi %r4,1 14: a7 58 00 02 lhi %r5,2 18: c0 e5 00 00 00 00 brasl %r14,18 <bla+0x18> 1e: 98 ef f0 98 lm %r14,%r15,152(%r15) 22: 07 fe br %r14 Not that it really matters, since other archs enforce the rule anyway. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html