Re: Prevent duplicate bus_space_map for TURBOchannel?

[David Brownlee <abs%netbsd.org@localhost>]

On 24 April 2016 at 13:16, Felix Deichmann <m4j0rd0m0%gmail.com@localhost> wrote:
> I seek developer advice regarding TURBOchannel support:
>
> Trying to use a TC driver under VAX, I hit the point where a "duplicate"
> bus_space_map is necessary/performed: The generic TC stuff in tc.c,
> especially tc_checkslot(), wants to access memory space by pointers and
> "linearly", so for VAX TC, I must map physical space before (which is the
> same as calling bus_space_map), for example in tc_vsbus.c before calling
> tcattach().
> The TC device drivers attached by tc(4) again will call bus_space_map, which
> can lead to multiple allocations of the same region.
>
> What would be the preferred solution here, also regarding the other TC
> platforms?
> Basically I'd tend towards code in tc.c which will map for itself there when
> accessing the option ROM, calling tc_badaddr etc., and cleanly unmap before
> attaching children?

You might want to ask on one of the more general tech-kern@ or similar
list - as the specific concepts are probably not VAX or even
TURBOchannel specific :)