On Friday, January 27, 2023 11:36 PM, Ferruh Yigit wrote:
> On 1/18/2023 6:00 AM, Jiawen Wu wrote:
> > When round up buffer size to 1K, to configure the register, hardware
> > will receive packets exceeding the buffer size in LRO mode. It will
> > cause a segment fault in the receive function.
> >
> > Fixes: be797cbf4582 ("net/txgbe: add Rx and Tx init")
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Jiawen Wu <jiawe...@trustnetic.com>
> > ---
> > drivers/net/txgbe/txgbe_rxtx.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/txgbe/txgbe_rxtx.c
> > b/drivers/net/txgbe/txgbe_rxtx.c index ac1bba08a3..ae70ca3beb 100644
> > --- a/drivers/net/txgbe/txgbe_rxtx.c
> > +++ b/drivers/net/txgbe/txgbe_rxtx.c
> > @@ -4382,7 +4382,7 @@ txgbe_dev_rx_init(struct rte_eth_dev *dev)
> > */
> > buf_size = (uint16_t)(rte_pktmbuf_data_room_size(rxq->mb_pool) -
> > RTE_PKTMBUF_HEADROOM);
> > - buf_size = ROUND_UP(buf_size, 0x1 << 10);
> > + buf_size = ROUND_DOWN(buf_size, 0x1 << 10);
> > srrctl |= TXGBE_RXCFG_PKTLEN(buf_size);
> >
>
> What if 'buf_size' is less than 1K, won't 'ROUND_DOWN' make it 0, and I assume
> setting 0 to register may cause problem.
>
It is indeed a problem, I will fix it.
> And according to the code comment for 'buf_size' [1], buffer size can't be
> more than
> 16K, but technically 'buf_size' can be more than 16K.
> Does the HW constrain values larger than 16K? If not the 'buf_size'
> value needs to be checked against the 16K limit.
>
There is a macro that defines the conversion to limit 16K.
#define PKTLEN(v) ROUND_OVER(v, 14, 10)
#define ROUND_OVER(x, maxbits, unitbits) \
((x) >= 1 << (maxbits) ? 0 : (x) >> (unitbits))
>
>
>
> [1]
> /*
> * Configure the RX buffer size in the PKTLEN field of
> * the RXCFG register of the queue.
> * The value is in 1 KB resolution. Valid values can be from
> * 1 KB to 16 KB.
> */
>
