Subject: Re: SMC91cxx h/w info and bus space queries
To: None <>
From: Izumi Tsutsui <>
List: tech-kern
Date: 07/27/2000 00:02:16
In <> wrote:

> 	* Should the driver do a le16toh() or htole16() in
> 	  conjunction with its current code?  That wouldn't
> 	  seem right for systems that automatically byte-swap
> 	  for the bus accesses.
> 	* Should the mac68k bus_space implementation be
> 	  expanded to carry flag(s) (in the bus_handle_t)
> 	  that drivers can set?  One of these flags would
> 	  be for byte swapping (there is some need also
> 	  for a way to specify that byte registers are on
> 	  longword boundaries, etc.).
> I'm thinking that the second is the way to go, but since
> it's more work and will have some negative impact on performance
> (on a machine with little performance to spare ;-), I'd like
> to hear what others think about this.

All byte-swap operations should be done inside bus_space functions,
so I believe the latter is proper. mac68k bus_space functions
should be implemented like amiga or atari to handle both endian.
I guess this is requred to support mac68k nubus wdc.
(MI wdc also requires "stride" (sparse space access) method, though.)
Izumi Tsutsui