Subject: Re: can't figure bus_space_map() out
To: Gregory McGarry <>
From: Alexander Funcke <>
List: tech-kern
Date: 04/18/2002 09:35:55
On Thu, Apr 18, 2002 at 08:14:59AM +1200, Gregory McGarry wrote:
> bus_space is for use on busses in MI code.  You're not attaching to
> a bus, you're not in MI code and uvm hasn't been launched yet.
> You'll have to pinch some kv space from the kernel, and map the page
> yourself.
> Do you really need to memory-map something at 2GB to launch the CPU?

The CPU has an integrated graphics-accelerator and kitchen-sink, the 
major usage of this 'register' is for the graphics as well as for some 
configuration stuff so I guess that's why it is as far off as 0x40000000.

But I don't need it to launch the CPU, but as a base address to offset
from for stuff later on. Is there a better place to do this init?

(The init is:
	I query the CPU to give me the address of 0x40000000 and 
	second, map it.


> 	-- Gregory McGarry <>