Re: [Qemu-devel] [PULL 14/28] exec: make address spaces 64-bit wide

[Mike Day]

"Michael S. Tsirkin" <address@hidden> writes:

> On Fri, Jan 10, 2014 at 08:31:36AM -0700, Alex Williamson wrote:

> Short term, just assume 48 bits on x86.
>
> We need to figure out what's the limitation on ppc and arm -
> maybe there's none and it can address full 64 bit range.
>
> Cc some people who might know about these platforms.

The document you need is here: 

http://goo.gl/fJYxdN

"PCI Bus Binding To: IEEE Std 1275-1994"

The short answer is that Power (OpenFirmware-to-PCI) supports both MMIO
and Memory mappings for BARs.

Also, both 32-bit and 64-bit BARs are required to be supported. It is
legal to construct a 64-bit BAR by masking all the high bits to
zero. Presumably it would be OK to mask the 16 high bits to zero as
well, constructing a 48-bit address.

Mike

-- 
Mike Day | "Endurance is a Virtue"