[PATCH 5/7] net/nfb: support setting Rx MTU

[Stephen Hemminger]

On Fri,  6 Feb 2026 18:04:33 +0100
spinler at cesnet.cz wrote:

> +static int
> +nfb_eth_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
> +{
> +	unsigned int i;
> +	struct nc_rxmac_status status;
> +	struct pmd_internals *intl = dev->process_private;
> +	uint16_t frame_length_max_capable;
> +
> +	mtu += RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
> +

Since mtu is 16 bit value, you need to use uint32_t to avoid
overflow.

Something like:
+	uint32_t frame_len = (uint32_t)mtu + RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
+	if (frame_len > priv->frame_len_max_cap)
+		return -EINVAL;

+	for (i = 0; i < intl->max_rxmac; ++i)
+		nc_rxmac_set_frame_length(intl->rxmac[i], frame_len, RXMAC_FRAME_LENGTH_MAX);