Re: [patch] fastcall-2.3.32-B6, SYSENTER/SYSEXIT support

Richard Gooch (rgooch@ras.ucalgary.ca)
Mon, 13 Dec 1999 16:05:57 -0700


Peter Samuelson writes:
>
> [me]
> > > We are still talking ia32 only, right? Because the SPARC people
> > > would *really* have fun with this sort of proposal....
>
> [Richard Gooch]
> > I don't see why it should be restricted to ia32. The technique can
> > just as easily be applied to other CPUs.
>
> If there are optimized system call paths for other archs that we
> might want to make use of. This came out of the discussion of how
> to make use of SYSENTER, after all.

It's not just about SYSENTER, though. It's about providing a framework
so that each syscall can be optimised in the best way *for that
syscall*, yet with a common ABI.

In some cases, a "syscall" won't actually involve a trap to the
kernel, such as gettimeofday(). This is something that would benefit
other architectures.

> > Why do you say the Sparc people would have fun? Is that "fun, as in
> > we can do neat tricks with this", or "fun, as in break out the
> > flamethrowers"?
>
> I was thinking that building the jump table on sparc{,64} would be
> complex because of their sparse syscall numbers. On second thought
> this wouldn't necessarily be the case.

I'm sure something can be arranged.

> But that brings up an interesting side issue: are we considering
> multiple PER_* or just PER_LINUX?

I think PER_LINUX is the important one. Besides, this whole proposal
involves changing the ABI, which we can do for PER_LINUX. For other
binary formats, we have to stick to their ABI. So I don't see how a
jump table would help here.

Regards,

Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/