Re: MI overrides of bus_dma(9), bus_space(9), pci(9)

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

On Wed, Mar 10, 2010 at 10:50 PM, Martin Husemann 
<martin%duskware.de@localhost> wrote:
> On Wed, Mar 10, 2010 at 09:46:03PM +0900, Masao Uebayashi wrote:
>> [..] For example,
>> bus_addr_t of a device instance should be taught to struct device as
>> an attribute (or property or whatever you call).
>
> What is *the* "bus_addr_t of a device instance"?

That depends.

And this answer has never been answered.  This is why we have all the
messy MD bus code like rbus...

>> Then we can have a
>> unified way to calculate the physical address of the device, by
>> summing up its parents' bus_addr_t.
>
> I'm neither sure this could be done on all archs,

It *should* be done on *all* archs.

> nor why you would want to do this at all.

Because NetBSD/arm (imx31) had no bus_space_mmap(9).  See

        grep -r bs_notimpl_bs_mmap sys/arch/arm

And

        sys/arch/mips/mips/bus_space_alignstride_chipdep.c

The problem is MD code is responsible to everything.

(And this is where I started being side-tracked horribly from XIP...)

Masao