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

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

On Wed, Mar 17, 2010 at 3:52 AM, Matt Thomas <matt%3am-software.com@localhost> 
wrote:
> However I think bus_space(9) needs a bus_space_alloc_tag which will allocates 
> like bus_space_alloc but returns that space in its own bus_space tag which 
> can be used to allocate pieces of that allocated region.  We'd also need a 
> bus_space_free_tag.

I really like this.  Bridges are given region(s) by its parent bus
controller / bridge.  Bridges are responsible to manage regions of its
child devices.  (Actually, this seems to answer part of vague
questions I'm having...)

That said, my knowledge of existing hardwares is limited.  Could you
show me examples how this works in various situations, pointed out in
the pmem(9) thread?  (Bus width, endian, ...)

        http://mail-index.netbsd.org/tech-kern/2008/03/28/msg000781.html

Masao