Re: [PATCH] Add FUTEX_CMP_REQUEUE futex op

[Ulrich Drepper <drepper@redhat.com>]

Andrew Morton wrote:

> and we're expecting the a's and b's to line up across all architectures and
> compiler options.  I thought that on some architectures that only works out
> if the function has a vararg declaration.

I never heard that.


> Does it do the right thing on stack-grows-up machines?

Would be only HP/PA and I don't see this to be a problem.


> If the compiler passes the first few args via registers and the rest on the
> stack, are we sure that it won't at some level of complexity decide to pass
> _all_ the args on the stack?  It's free to do so, I think.

This is not how the calling conventions are designed.  If registers are
used they happens unconditional of the remainder of the parameter list.
 The stack is used as an overflow.


> I have a vague memory of getting bitten by this trick once...

I don't and, as Ingo mentioned, we already did it before.

-- 
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖