Re: possible dmar_init_reserved_ranges() error

[Bjorn Helgaas]

Hi Ashok,

On Thu, Dec 22, 2016 at 03:45:08PM -0800, Raj, Ashok wrote:
> Hi Bjorn
> 
> None in the platform group say they know about this. So i'm fairly sure
> we don't do that on Intel hardware (x86). 

I'm pretty sure there was once an x86 prototype for which PCI bus
addresses were not identical to CPU physical addresses, but I have no
idea whether it shipped that way.

Even if such a system never shipped, the x86 arch code supports _TRA,
and there's no reason to make the unnecessary assumption in this code
that _TRA is always zero.

If we didn't want to use pcibios_resource_to_bus() here for some
reason, we should at least add a comment about why we think it's OK to
use a CPU physical address as an IOVA.

Bjorn