On Tue, 25 Aug 1998 09:49:10 +0900 
 Ken Nakata <kenn@synap.ne.jp> wrote:

 > OTOH, atari bus_space_tag_t is a huge struct full of pointers to
 > bus_space_{read,write}* methods, and any bus_space_{read,write}* call
 > always involves at least one level of memory indirect reference.
 > Wouldn't you call this a performance hit, when compared to what we
 > have in mac68k now?
 > 
 > Perhaps this cost is justified on atari since ataris have ISA bus, but
 > AFAIK, IDE bus is _the_ _only_ LE bus present in any 68k Mac model,
 > and I just don't think it's worth converting mac68k bus_space
 > implementation into something like atari's only for using the MI wdc.c
 > without modification.  I'm not sure what Scott (Reynolds, mac68k
 > portmaster) would think, but at least for now, I opt for keeping a
 > separate copy of wdc.c in arch/mac68k/dev.

So what you want is a structure like the atari has, and if the pointer
to it is NULL, use the current inlined versions, else call through the
structure.

That's only an extra test ... shouldn't be too bad.

Jason R. Thorpe                                       thorpej@nas.nasa.gov
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