Copy linear layout to CCW, MMIO sections.

Revision r49 "virtqueue: flexible layout, size, alignment" moved the linear
assumption into the legacy section.  We also need it in the per-transport
sections until (if?) those two transports go non-linear.

Just copied the paragraph, with variable names changed to match the particular
transport field nomenclature.

Signed-off-by: Rusty Russell <rusty@au1.ibm.com>

git-svn-id: https://tools.oasis-open.org/version-control/svn/virtio@52 0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652

1 files changed, 41 insertions, 0 deletions

diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt
index 73e1e8b..b5a5835 100644
--- a/virtio-v1.0-wd01-part1-specification.txt
+++ b/virtio-v1.0-wd01-part1-specification.txt
@@ -1396,6 +1396,27 @@ Writing to registers described as “R” and reading from
 registers described as “W” is not permitted and can cause
 undefined behavior.
 
+100.3.2.2.1.  Virtqueue Layout
+------------------------------
+
+The virtqueue is physically contiguous, with padded added to make the
+used ring meet the QueueAlign value:
+
++-------------------+-----------------------------------+-----------+
+| Descriptor Table  |   Available Ring     (padding)    | Used Ring |
++-------------------+-----------------------------------+-----------+
+
+The calculation for total size is as follows:
+
+	#define ALIGN(x) (((x) + QueueAlign) & ~QueueAlign)
+	static inline unsigned vring_size(unsigned int QueueNum)
+	{
+	     return ALIGN(sizeof(struct vring_desc)*QueueNum
+			  + sizeof(u16)*(3 + QueueNum))
+	          + ALIGN(sizeof(u16)*3 + sizeof(struct vring_used_elem)*QueueNum);
+	}
+
+
 2.3.2.3. MMIO-specific Initialization And Device Operation
 ---------------------------------------------------------
 
@@ -1542,6 +1563,26 @@ queue contains the guest address for queue index. The actual
 number of allocated buffers is transmitted in num and their
 alignment in align.
 
+100.3.3.2.1.  Virtqueue Layout
+------------------------------
+
+The virtqueue is physically contiguous, with padded added to make the
+used ring meet the align value:
+
++-------------------+-----------------------------------+-----------+
+| Descriptor Table  |   Available Ring     (padding)    | Used Ring |
++-------------------+-----------------------------------+-----------+
+
+The calculation for total size is as follows:
+
+	#define ALIGN(x) (((x) + align) & ~align)
+	static inline unsigned vring_size(unsigned int num)
+	{
+	     return ALIGN(sizeof(struct vring_desc)*num
+			  + sizeof(u16)*(3 + num))
+	          + ALIGN(sizeof(u16)*3 + sizeof(struct vring_used_elem)*num);
+	}
+
 2.3.3.2.2. Communicating Status Information
 -------------------------------------------