Re: /dev/vme*

[Bolo <bolo%cs.wisc.edu@localhost>]

> > 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.

Bolo