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> > My guess is that they generate the alternate vmebus bus cycle codes
> > needed to access vmebus devices with 16bit address/data regsiters.
> They just allow mapping a different range. That could be allowed for
> /dev/mem directly as well. That's why I don't see the point in the
> additional devices.
My suns are off at the moment, and I don't have current source handy,
but this may be applicable:
1) it would probably break SunOS executable compatability. The
execs can't open the vme address space to access the
vme resources there properly.
2) IIRC (and it has been a long time) parts of the address space of
the suns are setup to access the VME bus with different widths. So,
yes all it does is map a different range, but that lets the hardware
do the accesses with the different widths.
The sun sbus and perhaps mbus memory access may have similar weird mappings,
but I never really had to deal with that.
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