Re: Don't save registers during system calls
H. Peter Anvin (hpa@transmeta.com)
Fri, 17 Apr 1998 03:41:42 -0700 (PDT)
> H Peter Anvin <hpa@transmeta.com> writes:
>
> |>> FWIW, the m68k port already essentially does this. On kernel entry it
> |>> only saves the registers that are call-clobbered in C (plus the registers
> |>> that contain the syscall arguments so that they can be accessed through
> |>> the normal C argument passing), the rest are only implicitly saved in the
> |>> normal stack frames and during context switch. Since the m68k has many
> |>> more registers than the ix86 this is a real win.
> |>>
>
> |> That's not quite what he's proposing. You're just doing the same
> |> thing, it's just that the saves are later. I think he was proposing
> |> that the kernel use a smaller (clobbered) register set than user space
> |> would, hence (hopefully) not needing to save and restore some of the
> |> registers at all. Since the Alpha has many more registers than the
> |> m68k, this might be a win, too.
>
> But that would only mean that you have to change the register allocation
> in the compiler. Or do i miss something?
So?
-hpa
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu