Adding support for XDP multi-buffer entails adding information of all
the fragments of the packet in the xdp_buff. This approach implies that
underlying buffer has to provide tailroom for skb_shared_info.
In the legacy-rx mode, driver can only configure upto 2k sized Rx buffers
and with the current configuration of 2k sized Rx buffers there is no way
to do tailroom reservation for skb_shared_info. Hence size of Rx buffers
is now lowered to 1664 (2k - sizeof(skb_shared_info)). Also, driver can
only chain upto 5 Rx buffers and this means max MTU supported for
legacy-rx is now 8320.
Signed-off-by: Tirthendu Sarkar <tirthendu.sarkar@xxxxxxxxx>
---
drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +-
drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 672038801d1d..d7c08f1d486a 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -2903,7 +2903,7 @@ static void i40e_sync_filters_subtask(struct i40e_pf *pf)
static u16 i40e_calculate_vsi_rx_buf_len(struct i40e_vsi *vsi)
{
if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX))
- return I40E_RXBUFFER_2048;
+ return I40E_RXBUFFER_1664;
return PAGE_SIZE < 8192 ? I40E_RXBUFFER_3072 : I40E_RXBUFFER_2048;
}
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index 768290dc6f48..1382efb43ffd 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -97,6 +97,7 @@ enum i40e_dyn_idx_t {
/* Supported Rx Buffer Sizes (a multiple of 128) */
#define I40E_RXBUFFER_256 256
#define I40E_RXBUFFER_1536 1536 /* 128B aligned standard Ethernet frame */
+#define I40E_RXBUFFER_1664 1664 /* For legacy Rx with tailroom for frags */
#define I40E_RXBUFFER_2048 2048
#define I40E_RXBUFFER_3072 3072 /* Used for large frames w/ padding */
#define I40E_MAX_RXBUFFER 9728 /* largest size for single descriptor */
--
2.34.1
