On Fri, 2007-03-02 at 16:52 -0800, Davide Libenzi wrote: > On Fri, 2 Mar 2007, Nicholas Miell wrote: > > > The point Ingo was making is that the x86 ABI already requires the FPU > > context to be saved before *all* function calls. > > I've not seen that among Ingo's points, but yeah some status is caller > saved. But, aren't things like status word and control bits callee saved? > If that's the case, it might require proper handling. >
Ingo mentioned it in one of the parts you cut out of your reply: > and here is where thinking about threadlets as a function call and not > as an asynchronous context helps alot: the classic gcc convention for > FPU use & function calls should apply: gcc does not call an external > function with an in-use FPU stack/register, it always neatly unuses it, > as no FPU register is callee-saved, all are caller-saved. The i386 psABI is ancient (i.e. it predates SSE, so no mention of the XMM or MXCSR registers) and a bit vague (no mention at all of the FP status word), but I'm fairly certain that Ingo is right. -- Nicholas Miell <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
