RE: [PATCH] net/nfp: set the appropriate initialized value of flbufsz

[Nole Zhang <peng.zhang@corigine.com>]

 > On 10/10/2022 7:48 AM, Chaoyong He wrote:
> > From: Peng Zhang <peng.zhang@corigine.com>
> >
> > When the testpmd app start-up with parameter max-pkt-len, it will set
> MTU.
> > But the initialized value of flubfsz is inappropriate, if the value of
> > flbufsz is smaller than the valude of max-pkt-len, the testpmd app
> > will start fail.
> >
> 
> What is the failure in the testpmd?

The log is as follows:
[root@volstruis ~]# dpdk-testpmd --main-lcore 10 -l 10,11,12 -n 4 -a 0000:81:00.0 --socket-mem 2048,2048 --proc-type auto -- --portmask 0x3 --nb-cores 2 --rxq 1 --txq 1 --rxd 1024 --txd 1024 --port-topology loop --forward-mode macswap  --max-pkt-len 9216 --mbuf-size 9600  --rss-udp --burst=32
EAL: Detected CPU lcores: 40
EAL: Detected NUMA nodes: 2
EAL: Auto-detected process type: PRIMARY
EAL: Detected static linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'VA'
EAL: VFIO support initialized
EAL: Using IOMMU type 1 (Type 1)
EAL: Probe PCI driver: net_nfp_pf (19ee:4000) device: 0000:81:00.0 (socket 1) NFP HWINFO header: 48490200
TELEMETRY: No legacy callbacks, legacy socket not created Set macswap packet forwarding mode
testpmd: create a new mbuf pool <mb_pool_1>: n=163456, size=9600, socket=1
testpmd: preferred mempool ops selected: ring_mp_mc Configuring Port 0 (socket 1)
Port0 dev_configure = -34
Fail to configure port 0
EAL: Error - exiting with code: 1
  Cause: Start ports failed

First  in the `nfp_net_configure()`, we will judge the value of MTU and hw->flbufsz, If MTU > hw->flbufsz, it will have the error.

And the `--max-pkt-len` is setting the MTU in the initialize process, the initialized  value of  hw->flbufsz is just 1500 at first.

So if we set the `max-pkt-len`  bigger than the initialized value of flbufsz, It will lead the error.

Hence we set the new value of hw->flbufsz, it can large the range max-pkt-len in the initialized process.


> 
> This patch is fixing something but it is not clear what is fixed, the concern is it
> may be changing driver to make something pass in test application (testpmd).
> 
> What is 'flubfsz', is it Hw configured frame buffer size?


It is configured in the `nfp_net_rx_queue_setup()`{`hw->flbufsz = rxq->mbuf_size`}.
If the rxq->mbuf_size < MTU, the MTU can't work.

> 
> 
> > Fixes: 5c305e218f15 ("net/nfp: fix initialization")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Peng Zhang <peng.zhang@corigine.com>
> > Reviewed-by: Chaoyong He <chaoyong.he@corigine.com>
> > Reviewed-by: Niklas Söderlund <niklas.soderlund@corigine.com>
> > ---
> >   drivers/net/nfp/nfp_ethdev.c    | 2 +-
> >   drivers/net/nfp/nfp_ethdev_vf.c | 2 +-
> >   2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/nfp/nfp_ethdev.c
> > b/drivers/net/nfp/nfp_ethdev.c index 5cdd34e588..b95e623f1f 100644
> > --- a/drivers/net/nfp/nfp_ethdev.c
> > +++ b/drivers/net/nfp/nfp_ethdev.c
> > @@ -517,7 +517,7 @@ nfp_net_init(struct rte_eth_dev *eth_dev)
> >       hw->cap = nn_cfg_readl(hw, NFP_NET_CFG_CAP);
> >       hw->max_mtu = nn_cfg_readl(hw, NFP_NET_CFG_MAX_MTU);
> >       hw->mtu = RTE_ETHER_MTU;
> > -     hw->flbufsz = RTE_ETHER_MTU;
> > +     hw->flbufsz = hw->max_mtu;
> >
> >       /* VLAN insertion is incompatible with LSOv2 */
> >       if (hw->cap & NFP_NET_CFG_CTRL_LSO2) diff --git
> > a/drivers/net/nfp/nfp_ethdev_vf.c b/drivers/net/nfp/nfp_ethdev_vf.c
> > index d304d78d34..47acb4c60e 100644
> > --- a/drivers/net/nfp/nfp_ethdev_vf.c
> > +++ b/drivers/net/nfp/nfp_ethdev_vf.c
> > @@ -396,7 +396,7 @@ nfp_netvf_init(struct rte_eth_dev *eth_dev)
> >       hw->cap = nn_cfg_readl(hw, NFP_NET_CFG_CAP);
> >       hw->max_mtu = nn_cfg_readl(hw, NFP_NET_CFG_MAX_MTU);
> >       hw->mtu = RTE_ETHER_MTU;
> > -     hw->flbufsz = RTE_ETHER_MTU;
> > +     hw->flbufsz = hw->max_mtu;
> >
> >       /* VLAN insertion is incompatible with LSOv2 */
> >       if (hw->cap & NFP_NET_CFG_CTRL_LSO2)