Re: IBM405GP/GPr OPB bus_space endian (powerpc/ibm4xx/dev/opb.c)

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

In article <43426BEC.2070005%netbsd.org@localhost>
shige%NetBSD.org@localhost wrote:

>  static struct powerpc_bus_space opb_tag = {
>       _BUS_SPACE_LITTLE_ENDIAN|_BUS_SPACE_MEM_TYPE,
>       0x0, IBM405GP_UART0_BASE, 0x1000
>  };
> 
> Why it is Little-Endian in spite of CPU byte-order (Big-Endian) ?
> Is there any special reason?

I think it's just because most powerpc ports (bebox, macppc etc.)
have only little endian bus like PCI, ISA, and obio.
(mvmeppc port doesn't support VME bus!?)

> If there is no reason, I want to change bus_space byte-order
> from Little to Big.
> Is it ok?

Maybe it's okay, but you may have to check if there are
any bus_space usage where stream ops are required in
existing opb drivers.
---
Izumi Tsutsui