Subject: Re: need advice regarding Au 1550 (MIPS) memory mapping
To: Garrett D'Amore <garrett_damore@tadpole.com>
From: Alex Pelts <alexp@broadcom.com>
List: port-mips
Date: 09/29/2005 20:44:28
Hmm,
I have no experience with that particular board but as far as I know
most mips systems have 32 bit address bus. What mips core is on that board?
If this is alchemy core it is only 14 bit address bus, so I can't see
how you can address 36bit address space. It also looks like 32 bit mips
which makes it questionable about 36 bit access as well.
I may be wrong here but I think you are mistaking about 36 bit address
space.
Regards,
Alex
Garrett D'Amore wrote:
> Hi all,
>
> I'm trying to add support for Au1500/1550 PCI. On the Au1550, PCI space
> is accessed from a 36-bit address space, where the upper 4 bits are
> nonzero. (In other words above 4GB.)
>
> What is not obvious to me is how do I arrange for access to such a
> physical address. The Au1550 spec says you have to use a TLB entry for
> this. I'm trying to figure out how to go about doing this within the
> NetBSD memory system.
>
> Anyone with experience doing similar things on other MIPS processors
> have any advice about what I should be looking at? FYI, this is my
> first experience with MIPS in nearly two decades, and I'm also new to
> NetBSD. Guess I could have picked an easier thing to start with, huh? :-)
>
> Thanks!
>
> -- Garrett
>
>
>
>