[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]

*Subject*: **Network Device virtqueue numbering**

*From*:**Ladi Prosek <lprosek@redhat.com>***To*: virtio-comment@lists.oasis-open.org*Date*: Wed, 18 May 2016 10:38:13 +0200

Hello virtio-comment, This is a comment on section "5.1.2 Network Device: virtqueues" of virtio 1.0 spec CS 04, copied below. The numbers don't add up. For 1-based N, receiveqN is at index 2N-2, transmitqN at index 2N-1 and controlq (if present) at index 2N. Specifically for the N=1 special case mentioned in the paragraph, controlq would be at index 2 and not 2*1+2 = 4. This could be fixed either by using the correct queue indices [2N-2, 2N-1, 2N] instead of [2N, 2N+1, 2N+2] or by switching to 0-based receiveq/transmitq numbering. Thanks! Ladi 5.1.2 Virtqueues 0 receiveq1 1 transmitq1 … 2N receiveqN 2N+1 transmitqN 2N+2 controlq N=1 if VIRTIO_NET_F_MQ is not negotiated, otherwise N is set by max_virtqueue_pairs. controlq only exists if VIRTIO_NET_F_CTRL_VQ set.

**Follow-Ups**:**Re: Network Device virtqueue numbering***From:*"Michael S. Tsirkin" <mst@redhat.com>

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]