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Should the TC accept changes listed in the description to resolve issue VIRTIO-154,
for inclusion in specification version(s) "virtio 1.1 cs01", and future versions of the specification?
Please vote Yes if you agree with all of the following.
If you disagree, please vote No.
If you don't have an opinion, please vote Abstain.
I move that:
The TC agrees to resolve the following specification issue:
VIRTIO-154: Document VIRTIO_F_IOMMU_PLATFORM reserved feature bit (33)
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On most virtio systems, physical addresses are provided from the driver
to the device and subsequently used to access memory directly. However,
some systems feature an IOMMU that complicates things slightly:
- The IOMMU might require configuration for DMA to work at all. Once
configured, the driver must pass bus addresses to the device, which
are then translated by the IOMMU into physical addresses in memory.
- The IOMMU might be bypassed by virtio DMA. In this case, physical
addresses must still be provided to the device by the driver, even
though an IOMMU appears to be present.
This has been solved by the addition of a new reserved feature bit,
VIRTIO_F_IOMMU_PLATFORM, to describe the two cases above. Legacy systems
will not negotiate the feature, and therefore continue to operate
directly on physical addresses.
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The TC accepts the following proposed changes to the specification:
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Document VIRTIO_F_IOMMU_PLATFORM that's already
in use by Linux guests.
See message:
Date: Thu, 20 Oct 2016 18:20:01 +0100
From: Will Deacon
To: virtio-dev@lists.oasis-open.org
Cc: Will Deacon , "Michael S. Tsirkin" , Stefan Hajnoczi
Subject: [PATCH v2] context: Document VIRTIO_F_IOMMU_PLATFORM reserved feature bit (33)
Message-Id:
https://lists.oasis-open.org/archives/virtio-dev/201610/msg00121.html
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The TC agrees to include the above change(s) in specification version(s) "virtio 1.1 cs01", and future versions of the
specification.
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Reminder: A Voting Member must be active in a TC to maintain voting rights. As
the Virtio TC has adopted a standing rule to conduct business only by
electronic ballot, without Meetings, a Voting Member who fails to cast a ballot
in two consecutive Work Product Ballots loses his or her voting rights at the
close of the second ballot missed.
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