Date: Mon, 8 Oct 2001 13:10:45 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: <cvs-committers@FreeBSD.org>, <cvs-all@FreeBSD.org> Subject: Re: cvs commit: src/sys/ia64/include cpufunc.h Message-ID: <20011008122319.M13486-100000@delplex.bde.org> In-Reply-To: <20011007123737.A380@athlon.pn.xcllnt.net>
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On Sun, 7 Oct 2001, Marcel Moolenaar wrote:
> On Sun, Oct 07, 2001 at 02:09:50PM +1000, Bruce Evans wrote:
> > bus_memio.h is supposed to just enable the memio functions in
> > bus_xyz${MACHINE}.h (I don't like this, but...).
> >
> > Why do you even need these functions?
>
> Because sys/dev/fb uses it (see below).
Ugh.
> > They are standard functions in
> > Linux, but in *BSD, drivers are supposed to use the bus_space functions
> > for all of them except memsetw. E.g., memsetw_io is spelled
> > bus_space_set_region_2 in *BSD, except the latter is more general (it
> > can handle both memory-mapped ioport-mapped i/o).
>
> Ok. This indicates that the functions I put in machine/cpufunc.h
> should actually be put in in a header in dev/fb (very likely
> dev/fb/fbreg.h).
I agree. It should its own macros to hide the complications of bus_space
if it wants to do that.
> > The alpha versions
> > of these functions actually seem to be compatibility cruft, mainly for
> > NetBSD.
>
> Above you say that drivers for *BSD are supposed to use the bus_space
> functions. This seems to contradict with the statement that we added
> the mem*io functions for compatibility with NetBSD on Alpha. This is
> fine, but it makes it all the harder for me to figure out what we call
> "right", so that I can do it right the first time.
I thought that the compatibility cruft was from NetBSD when I wrote my
original reply. It was actually added by dfr in rev.1.6 of
alpha/include/bus.h. The main problem now is that we have arch-dependent
compatibility cruft, so using it not only prolongs the like of the old
interfaces but requires messy ifdefs to select a set of interfaces.
> > Well, I almost see the reason -- on ia64's, the bus space interfaces
> > are implemented using the primitives in cpufunc.h instead of repeating
> > lots of code and writing loops in asm (there are no inline asms in the
> > ia64 bus.h).
>
> The bus_space_*_multi* functions will benefit a lot if don't use
> the primitives in the way we do now or in the form we now have them.
> See also below.
I couldn't quite see a continuation below :-). I think you just mean
that the bus_space_*_multi* functions really shouldn't exist. They
are very easy to synthesize using for loops, and that's exactly how
they are implemented except on i386's.
Bruce
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