diff options
Diffstat (limited to 'virtio-spec.txt')
| -rw-r--r-- | virtio-spec.txt | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/virtio-spec.txt b/virtio-spec.txt index 6bf1ca8..3b5cb18 100644 --- a/virtio-spec.txt +++ b/virtio-spec.txt @@ -295,10 +295,10 @@ is ignored. 2.1.4.4 The Virtqueue Available Ring ------------------------------------ -The available ring refers to what descriptors we are offering the -device: it refers to the head of a descriptor chain. The “flags” field +The available ring refers to what descriptor chains we are offering the +device: each entry refers to the head of a descriptor chain. The “flags” field is currently 0 or 1: 1 indicating that we do not need an interrupt -when the device consumes a descriptor from the available +when the device consumes a descriptor chain from the available ring. Alternatively, the guest can ask the device to delay interrupts until an entry with an index specified by the “used_event” field is written in the used ring (equivalently, until the idx field in the @@ -493,7 +493,7 @@ above. A naive implementation would do the following: avail->ring[avail->idx % qsz] = head; -However, in general we can add many descriptors before we update +However, in general we can add many descriptor chains before we update the “idx” field (at which point they become visible to the device), so we keep a counter of how many we've added: @@ -503,7 +503,7 @@ device), so we keep a counter of how many we've added: ---------------------------------- Once the index field of the virtqueue is updated, the device will -be able to access the descriptor entries we've created and the +be able to access the descriptor chains we've created and the memory they refer to. This is why a memory barrier is generally used before the index update, to ensure it sees the most up-to-date copy. @@ -1090,7 +1090,7 @@ Discovering what devices are available and their type is bus-dependent. +------------+--------------------+ | 11 | rproc serial | +------------+--------------------+ -| 12 | CAIF | +| 12 | virtio CAIF | +------------+--------------------+ 2.5.1 Network Device |