amd64 syscall.c question

I posted this to tech-kern, but I meant to send it to this list as well.

I know so little assembly that I need someone to clue me in on whether
my concern is out in left field.

Anyway, this is my original message:


I'm just wondering whether or not, in
syscall_fancy()/syscall_plain(), rval[1] should be assigned 0 or
frame->tf_rdx?  And should child_return() set tf_rdx=0 (as it is), or
to 1?  I can't seem to find a straight answer on google (read: this is
too new to me for me to be certain from reading the code alone).

Just wanted to make sure there wasn't a bug lurking.

Thanks,

--Blair