pull deps in for optimization, maybe slice back out later

overlay/virtqueue/used_element.go

@@ -0,0 +1,17 @@
+package virtqueue
+
+// usedElementSize is the number of bytes needed to store a [UsedElement] in
+// memory.
+const usedElementSize = 8
+
+// UsedElement is an element of the [UsedRing] and describes a descriptor chain
+// that was used by the device.
+type UsedElement struct {
+	// DescriptorIndex is the index of the head of the used descriptor chain in
+	// the [DescriptorTable].
+	// The index is 32-bit here for padding reasons.
+	DescriptorIndex uint32
+	// Length is the number of bytes written into the device writable portion of
+	// the buffer described by the descriptor chain.
+	Length uint32
+}