On 8/20/21 2:48 PM, Andrew Rybchenko wrote:
> From: Ivan Ilchenko <ivan.ilche...@oktetlabs.ru>
>
> Report max/min/align descriptors limits in device info get callback.
> Before calling the callback, rte_eth_dev_info_get() provides
> default values of nb_min as zero and nb_max as UINT16_MAX that are
> not correct for the driver, so one can't rely on them.
>
> Signed-off-by: Ivan Ilchenko <ivan.ilche...@oktetlabs.ru>
> Signed-off-by: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>
> ---
> drivers/net/virtio/virtio_ethdev.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/drivers/net/virtio/virtio_ethdev.c
> b/drivers/net/virtio/virtio_ethdev.c
> index e58085a2c9..601c03e079 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -33,6 +33,7 @@
> #include "virtio_logs.h"
> #include "virtqueue.h"
> #include "virtio_rxtx.h"
> +#include "virtio_rxtx_simple.h"
> #include "virtio_user/virtio_user_dev.h"
>
> static int virtio_dev_configure(struct rte_eth_dev *dev);
> @@ -2536,6 +2537,30 @@ virtio_dev_info_get(struct rte_eth_dev *dev, struct
> rte_eth_dev_info *dev_info)
> if ((host_features & tso_mask) == tso_mask)
> dev_info->tx_offload_capa |= DEV_TX_OFFLOAD_TCP_TSO;
>
> + if (host_features & (1ULL << VIRTIO_F_RING_PACKED)) {
> + /*
> + * According to 2.7 Packed Virtqueues,
> + * 2.7.10.1 Structure Size and Alignment:
> + * The Queue Size value does not have to be a power of 2.
> + */
> + dev_info->rx_desc_lim.nb_max = UINT16_MAX;
> + } else {
> + /*
> + * According to 2.6 Split Virtqueues:
> + * Queue Size value is always a power of 2. The maximum Queue
> + * Size value is 32768.
> + */
> + dev_info->rx_desc_lim.nb_max = 32768;
> + }
> + /*
> + * Actual minimum is not the same for virtqueues of different kinds,
> + * but to avoid tangling the code with separate branches, rely on
> + * default thresholds since desc number must be at least of their size.
> + */
> + dev_info->rx_desc_lim.nb_min = RTE_MAX(DEFAULT_RX_FREE_THRESH,
> + RTE_VIRTIO_VPMD_RX_REARM_THRESH);
> + dev_info->rx_desc_lim.nb_align = 1;
> +
It makes sense, but shouldn't we do the same for dev_info->tx_desc_lim?
> return 0;
> }
>
>
