Re: [Qemu-devel] [PATCH 8/8] Make dma_addr_t 64 bit always

[David Gibson]

On Sun, Feb 26, 2012 at 09:46:52PM +0000, Blue Swirl wrote:
> On Fri, Feb 24, 2012 at 04:57, David Gibson <address@hidden> wrote:
> > On Fri, Feb 24, 2012 at 02:27:43PM +1100, David Gibson wrote:
> >
> > Oops, ignore this one folks.  As is probably obvious, this was a
> > testing patch not meant to go into the main series.
> 
> Actually I'm not sure what would be the correct way to calculate the
> size. For example, on Sparc32 the virtual address space and CPU
> registers are 32 bits, physical address space 36 bits, but device
> virtual memory address space (DVMA, used by devices to talk to IOMMU)
> is only 32 bits.

Well, yes, in fact I think we probably do need to use 64-bit addresses
always (or at least whenever we have any kind of IOMMU support
available), because it's almost impossible to be certain that a
platform could never have a 64-bit bus of some kind plugged in.

But that's a matter for another day.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson