Benjamin Herrenschmidt wrote:
On Wed, 2008-10-22 at 08:08 -0500, Kumar Gala wrote:
We are developing a board based on Freescale 8641D which can get
4GB
of ram. So I need 4GB+IOs (~1GB) of physical addressing space.
My plan is to put a part of this ram above of 4GB to keep accesses
to the IOs below the 4GB limit. It means non-contiguous ram
addressing and XAEN features to be working.
Why would you put the IOs below the 4G point ? It's actually easier
to have the IOs up above, like a lot of 4xx do.
Because we're Genesi! And we have a firmware solution that
kind of has to keep 32-bit pointers in the unlikely event that
someone actually uses the client interface (besides yaboot!).
Having I/O in the 36-bit range could cause all sorts of
explosions, and we're running real-mode so trapping and faking
I/O accesses is REALLy difficult :}
--
Matt Sealey <[EMAIL PROTECTED]>
Genesi, Manager, Developer Relations
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