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Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support
From: |
Chris Wright |
Subject: |
Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support |
Date: |
Thu, 15 Jul 2010 10:17:10 -0700 |
User-agent: |
Mutt/1.5.20 (2009-08-17) |
* Avi Kivity (address@hidden) wrote:
> On 07/15/2010 07:52 PM, Chris Wright wrote:
> >
> >>Really? Can you provide an documentation to support this claim?
> >>My impression is that there is no difference between translated and
> >>untranslated devices, and the translation is explicitly disabled by
> >>software.
> >ATS allows an I/O device to request a translation from the IOMMU.
> >The device can then cache that translation and use the translated address
> >in a PCIe memory transaction. PCIe uses a couple of previously reserved
> >bits in the transaction layer packet header to describe the address
> >type for memory transactions. The default (00) maps to legacy PCIe and
> >describes the memory address as untranslated. This is the normal mode,
> >and could then incur a translation if an IOMMU is present and programmed
> >w/ page tables, etc. as is passes through the host bridge.
> >
> >Another type is simply a transaction requesting a translation. This is
> >new, and allows a device to request (and cache) a translation from the
> >IOMMU for subsequent use.
> >
> >The third type is a memory transaction tagged as already translated.
> >This is the type of transaction an ATS capable I/O device will generate
> >when it was able to translate the memory address from its own cache.
> >
> >Of course, there's also an invalidation request that the IOMMU can send
> >to ATS capable I/O devices to invalidate the cached translation.
>
> For emulated device, it seems like we can ignore ATS completely, no?
Not if you want to emulate an ATS capable device ;)
Eariler upthread I said:
IOW, if qemu ever had a device with ATS support...
So, that should've been a much bigger _IF_
thanks,
-chris
- Re: [Qemu-devel] [RFC PATCH 3/7] pci: call IOMMU hooks, (continued)
- [Qemu-devel] [RFC PATCH 4/7] ide: IOMMU support, Eduard - Gabriel Munteanu, 2010/07/14
- [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Paul Brook, 2010/07/14
- [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Joerg Roedel, 2010/07/14
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Paul Brook, 2010/07/14
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Anthony Liguori, 2010/07/14
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Chris Wright, 2010/07/14
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Paul Brook, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Chris Wright, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Avi Kivity, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support,
Chris Wright <=
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Avi Kivity, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Chris Wright, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Eduard - Gabriel Munteanu, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Joerg Roedel, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Chris Wright, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Joerg Roedel, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Anthony Liguori, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Joerg Roedel, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Eduard - Gabriel Munteanu, 2010/07/15
- Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support, Anthony Liguori, 2010/07/15