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Re: [Qemu-devel] RFC: vfio API changes needed for powerpc
From: |
Stuart Yoder |
Subject: |
Re: [Qemu-devel] RFC: vfio API changes needed for powerpc |
Date: |
Wed, 3 Apr 2013 13:25:26 -0500 |
>> > Type1 is arbitrary. It might as well be named "brown" and this one
>> > can be
>> > "blue".
>>
>> The difference is that "type1" seems to refer to hardware that can do
>> arbitrary 4K page mappings, possibly constrained by an aperture but
>> nothing else. More than one IOMMU can reasonably fit that. The odds
>> that another IOMMU would have exactly the same restrictions as PAMU
>> seem smaller in comparison.
>>
>> In any case, if you had to deal with some Intel-only quirk, would it
>> make sense to call it a "type1 attribute"? I'm not advocating one way
>> or the other on whether an abstraction is viable here (though Stuart
>> seems to think it's "highly unlikely anything but a PAMU will comply"),
>> just that if it is to be abstracted rather than a hardware-specific
>> interface, we need to document what is and is not part of the
>> abstraction. Otherwise a non-PAMU-specific user won't know what they
>> can rely on, and someone adding support for a new windowed IOMMU won't
>> know if theirs is close enough, or they need to introduce a "type3".
>
> So Alexey named the SPAPR IOMMU something related to spapr...
> surprisingly enough. I'm fine with that. If you think it's unique
> enough, name it something appropriately. I haven't seen the code and
> don't know the architecture sufficiently to have an opinion.
The only reason I suggested "type 2" is that I thought that was the
convention...we would enumerate different iommus. I think that
calling it "pamu" is better and more clear.
Stuart
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, (continued)
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Scott Wood, 2013/04/03
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Alex Williamson, 2013/04/03
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Scott Wood, 2013/04/03
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Scott Wood, 2013/04/03
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Stuart Yoder, 2013/04/03
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Scott Wood, 2013/04/03
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Scott Wood, 2013/04/02
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Alex Williamson, 2013/04/02
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Scott Wood, 2013/04/02
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Alex Williamson, 2013/04/02
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc,
Stuart Yoder <=
- Re: [Qemu-devel] RFC: vfio API changes needed for powerpc, Scott Wood, 2013/04/03