"Maciej W. Rozycki" wrote: > > On Fri, 25 May 2001, Jun Sun wrote: > > > Alright, I rolled my sleeve and digged into IRIX 6.5, and guess what? > > sysmips() does NOT have MIPS_ATOMIC_SET (2001) on IRIX! See the header below. > > I remember Ralf writing of this being a compatibility call with RISC/OS > (is it the original OS of MIPS, Inc.?), IIRC. Ralf: am I right? > > > So apparently MIPS_ATOMIC_SET was invented for Linux only, probably just to > > implement _test_and_set(). (It would be interesting to see how IRIX implement > > _test_and_set() on MIPS I machines. However, the machine I have access uses > > ll/sc instructions). > > Does IRIX actually run on anything below ISA II? > I assume nobody answering the above questions means nobody really care. So we can safely move ahead without worrying about them. :-) > > To me, either 1.a) or 2) is fine with me, although I have a slight faovr over > > 2) (perhaps because I don't like assembly code and the extra "vertical" > > calling layer introduced in 1.a) > > What about 3) -- a new syscall with a different semantics and no need to > care about limitations of current implementations (especially the > sysmips() bag). Having a new syscall is fine with me, although seems a little more instrusive than adding a subcall to sysmips(). > I've just sent a proposal for discussion. I'm looking > forward for constructive feedback. > The patch looks good to me. BTW, why wouldn't you choose to have three arguments in the syscall, where the last one is a pointer to the variable to hold the return value? Doing that would avoid tricky register manipulation on both calling side (fetching return value from $v1) and kernel side (setting regs.regs[3]). Jun
