Re: bus_space(9) overrides & resource reservations

[Eduardo Horvath <eeh%NetBSD.org@localhost>]

On Thu, 27 May 2010, David Young wrote:

> On Thu, May 27, 2010 at 10:18:53PM +0900, Izumi Tsutsui wrote:
> > > What are the arguments to bus_space_tag_create()?
> > > 
> > > I'm looking for a flag to tell it the "bus endianess" of the resulting 
> > > tag,
> > > as that would help to sort out an abstraction violation in SBUS <-> pcmcia
> > > adapters. Support for that would be optional, of course.
> > 
> > I doubt we will able to abstruct various bus quirks including
> > endianness with such simple flags.
> 
> You would not use flags, you would install an override function to be
> used instead of bus_space_read_4().

Uh, no you wouldn't.  Endianness is set by MMU mappings when the registers 
are mapped in.  Using the bswap routines on sparc64 is extremely 
inefficient since they result in 4-8 dependent instructions vs 0 cycles 
using the mux in the load/store path.

Eduardo