Luck, Tony wrote: >> It doesn't look like the return value (r8) is actually being set beyond >> initialized to 0. If there is some ia64 instruction that modifies it, GCC >> doesn't know about it from the inline assembly (r8 doesn't appear in the >> inputs/outputs list). From looking at the x86 version (agh, inline asm is >> hard to parse), it does modify the return value based on whether the >> comparison was a success or not, and the return value is certainly used by >> the callers. > > The commit comment for the change makes it sound like the return value > is an error code (-ENOSYS if the function isn't implemented/configured; > -EFAULT if the user address is bogus) - or zero if nothing bad happened. Yes, that's right. > Not "the comparison was a success or not". > > What's the real answer? The ia64 code is returning 0 regardless of whether the > compare/exchange found the old value or not. Is this a bad assumption? No, I think something else is wrong, though I don't know what it would be. Émeric, was the bisection result reproducible? E.g., if you try building 37a9d912b24f and 37a9d912b24f^ again, does the former consistently produce and the latter consistently not produce a crashy system? -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html