On Mon, 7 Aug 2000, Todd Vierling wrote:

> On Mon, 7 Aug 2000, Bill Studenmund wrote:
> 
> : > : > > I think adding something like -mlong-call and __attribute__ ((short-call))
> : > : > > would be the most efficient thing. :-)
> : 
> : Oops! This option would ONLY be for the LKM's, not the kernel compile. :-)
> 
> However, does this mean that there's a `different' calling convention for
> the kernel vs. LKMs?  i.e. stack has `more' on it with one method than the
> other, you can't just rts from long-call code into shortcall.  An example of
> `incompatible' calling conventions is the m68020 CALLM/RTM vs. the usual
> [JB]SR/RTS.

I hope not. If that's what long-call means, then that's not what we want.

The intent was to use "long-call" to tell the compiler that when it makes
a call TO this fucntion (or with -mlong-call, when it makes a call to all
functions), it uses the can-jump-anyhwere-in-4GB method. I lost a quote of
the asm's 4 instructions, but it loads a register, then jups to the
address in the register.

As I understand it, to the callee, it looks the same as if the 24-bit
relative subroutine call had been used. So routine exit is the same.

> : Also, could we teach all other ports about it, -mlong-call (and to ignore
> : it), or make some sort of include file magic happen?
> 
> That's probably not the best idea; you're probably better off adding it to
> <bsd.kmod.mk>, which is used by LKMs to build.  Additional CFLAGS can easily
> be added there.

Probably better. :-)

Take care,

Bill