-----Original Message-----
From: joro@8bytes.org [mailto:joro@8bytes.org]
Sent: Tuesday, October 08, 2013 10:32 PM
To: Bjorn Helgaas
Cc: Bhushan Bharat-R65777; alex.williamson@redhat.com; benh@kernel.crashi=

ng.org;

galak@kernel.crashing.org; linux-kernel@vger.kernel.org; linuxppc-
dev@lists.ozlabs.org; linux-pci@vger.kernel.org; agraf@suse.de; Wood Scot=

t-

B07421; iommu@lists.linux-foundation.org
Subject: Re: [PATCH 1/7] powerpc: Add interface to get msi region informa=

tion

=20
On Tue, Oct 08, 2013 at 10:47:49AM -0600, Bjorn Helgaas wrote:

quoted

I still have no idea what an "aperture type IOMMU" is, other than that
it is "different."

=20
An aperture based IOMMU is basically any GART-like IOMMU which can only r=

emap a

small window (the aperture) of the DMA address space. DMA outside of that=

 window

is either blocked completly or passed through untranslated.

It is completely blocked for Freescale PAMU.=20
So for this type of iommu what we have to do is to create a MSI mapping jus=
t after guest physical address, Example: guest have a 512M of memory then w=
e create window of 1G (because of power of 2 requirement), then we have to =
FIT MSI just after 512M of guest.
And for that we need
	1) to know the physical address of MSI's in interrupt controller (for that=
 this patch was all about of).

	2) When guest enable MSI interrupt then we write MSI-address and MSI-DATA =
in device. The discussion with Alex Williamson is about that interface.

Thanks
-Bharat

=20
=20
	Joerg
=20
=20