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47 lines
1.8 KiB
Rust
47 lines
1.8 KiB
Rust
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// Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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//
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// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
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//! Virtio queue related constant definitions
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/// Marks a buffer as continuing via the next field.
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pub const VIRTQ_DESC_F_NEXT: u16 = 0x1;
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/// Marks a buffer as device write-only.
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pub const VIRTQ_DESC_F_WRITE: u16 = 0x2;
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/// Shows that the buffer contains a list of buffer descriptors.
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pub const VIRTQ_DESC_F_INDIRECT: u16 = 0x4;
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/// Used flags
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pub const VIRTQ_USED_F_NO_NOTIFY: u16 = 0x1;
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/// This is the size of one element in the used ring, id (le32) + len (le32).
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pub(crate) const VIRTQ_USED_ELEMENT_SIZE: u64 = 8;
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/// Used ring header: flags (u16) + idx (u16)
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pub(crate) const VIRTQ_USED_RING_HEADER_SIZE: u64 = 4;
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/// This is the size of the used ring metadata: header + avail_event (le16).
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/// The total size of the used ring is:
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/// VIRTQ_USED_RING_HMETA_SIZE + VIRTQ_USED_ELEMENT_SIZE * queue_size
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pub(crate) const VIRTQ_USED_RING_META_SIZE: u64 = VIRTQ_USED_RING_HEADER_SIZE + 2;
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/// This is the size of one element in the available ring (le16).
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pub(crate) const VIRTQ_AVAIL_ELEMENT_SIZE: u64 = 2;
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/// Avail ring header: flags(u16) + idx(u16)
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pub(crate) const VIRTQ_AVAIL_RING_HEADER_SIZE: u64 = 4;
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/// This is the size of the available ring metadata: header + used_event (le16).
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/// The total size of the available ring is:
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/// VIRTQ_AVAIL_RING_META_SIZE + VIRTQ_AVAIL_ELEMENT_SIZE * queue_size
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pub(crate) const VIRTQ_AVAIL_RING_META_SIZE: u64 = VIRTQ_AVAIL_RING_HEADER_SIZE + 2;
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/// The Virtio Spec 1.0 defines the alignment of VirtIO descriptor is 16 bytes,
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/// which fulfills the explicit constraint of GuestMemory::read_obj().
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pub(crate) const VIRTQ_DESCRIPTOR_SIZE: usize = 16;
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/// Vector value used to disable MSI for a queue.
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pub const VIRTQ_MSI_NO_VECTOR: u16 = 0xffff;
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