[dpdk-stable] [PATCH] net/af_xdp: fix support of secondary process

[dpdk-stable] [PATCH] net/af_xdp: fix support of secondary process

[Stephen Hemminger]

Doing basic operations like info_get or get_stats was broken
in af_xdp PMD. The info_get would crash because dev->device
was NULL in secondary process. Fix this by doing same initialization
as af_packet and tap devices.

The get_stats would crash because the XDP socket is not open in
primary process. As a workaround don't query kernel for dropped
packets when called from secondary process.

Note: this does not address the other bug which is that transmitting
in secondary process is broken because the send() in tx_kick
will fail because XDP socket fd is not valid in secondary process.

Bugzilla ID: 805
Fixes: f1debd77efaf ("net/af_xdp: introduce AF_XDP PMD")
Cc: stable@dpdk.org
Cc: xiaolong.ye@intel.com
Ciara Loftus <ciara.loftus@intel.com>
Qi Zhang <qi.z.zhang@intel.com>
Anatoly Burakov <anatoly.burakov@intel.com>

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/net/af_xdp/rte_eth_af_xdp.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
index 74ffa4511284..70abc14fa753 100644
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -860,7 +860,7 @@ eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
 	struct pkt_rx_queue *rxq;
 	struct pkt_tx_queue *txq;
 	socklen_t optlen;
-	int i, ret;
+	int i;
 
 	for (i = 0; i < dev->data->nb_rx_queues; i++) {
 		optlen = sizeof(struct xdp_statistics);
@@ -876,13 +876,12 @@ eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
 		stats->ibytes += stats->q_ibytes[i];
 		stats->imissed += rxq->stats.rx_dropped;
 		stats->oerrors += txq->stats.tx_dropped;
-		ret = getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
-				XDP_STATISTICS, &xdp_stats, &optlen);
-		if (ret != 0) {
-			AF_XDP_LOG(ERR, "getsockopt() failed for XDP_STATISTICS.\n");
-			return -1;
-		}
-		stats->imissed += xdp_stats.rx_dropped;
+
+		/* The socket fd is not valid in secondary process */
+		if (rte_eal_process_type() != RTE_PROC_SECONDARY &&
+		    getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
+			       XDP_STATISTICS, &xdp_stats, &optlen) == 0)
+			stats->imissed += xdp_stats.rx_dropped;
 
 		stats->opackets += stats->q_opackets[i];
 		stats->obytes += stats->q_obytes[i];
@@ -1799,7 +1798,9 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
 			AF_XDP_LOG(ERR, "Failed to probe %s\n", name);
 			return -EINVAL;
 		}
+		/* TODO: reconnect socket from primary */
 		eth_dev->dev_ops = &ops;
+		eth_dev->device = &dev->device;
 		rte_eth_dev_probing_finish(eth_dev);
 		return 0;
 	}
-- 
2.30.2

Re: [dpdk-stable] [PATCH] net/af_xdp: fix support of secondary process

[Ferruh Yigit]

On 9/3/2021 5:15 PM, Stephen Hemminger wrote:
> Doing basic operations like info_get or get_stats was broken
> in af_xdp PMD. The info_get would crash because dev->device
> was NULL in secondary process. Fix this by doing same initialization
> as af_packet and tap devices.
> 
> The get_stats would crash because the XDP socket is not open in
> primary process. As a workaround don't query kernel for dropped
> packets when called from secondary process.
> 
> Note: this does not address the other bug which is that transmitting
> in secondary process is broken because the send() in tx_kick
> will fail because XDP socket fd is not valid in secondary process.
> 
> Bugzilla ID: 805
> Fixes: f1debd77efaf ("net/af_xdp: introduce AF_XDP PMD")
> Cc: stable@dpdk.org
> Cc: xiaolong.ye@intel.com
> Ciara Loftus <ciara.loftus@intel.com>
> Qi Zhang <qi.z.zhang@intel.com>
> Anatoly Burakov <anatoly.burakov@intel.com>
> 

+cc Ciara, Qi & Anatoly

> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  drivers/net/af_xdp/rte_eth_af_xdp.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
> index 74ffa4511284..70abc14fa753 100644
> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -860,7 +860,7 @@ eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
>  	struct pkt_rx_queue *rxq;
>  	struct pkt_tx_queue *txq;
>  	socklen_t optlen;
> -	int i, ret;
> +	int i;
>  
>  	for (i = 0; i < dev->data->nb_rx_queues; i++) {
>  		optlen = sizeof(struct xdp_statistics);
> @@ -876,13 +876,12 @@ eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
>  		stats->ibytes += stats->q_ibytes[i];
>  		stats->imissed += rxq->stats.rx_dropped;
>  		stats->oerrors += txq->stats.tx_dropped;
> -		ret = getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
> -				XDP_STATISTICS, &xdp_stats, &optlen);
> -		if (ret != 0) {
> -			AF_XDP_LOG(ERR, "getsockopt() failed for XDP_STATISTICS.\n");
> -			return -1;
> -		}
> -		stats->imissed += xdp_stats.rx_dropped;
> +
> +		/* The socket fd is not valid in secondary process */
> +		if (rte_eal_process_type() != RTE_PROC_SECONDARY &&
> +		    getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
> +			       XDP_STATISTICS, &xdp_stats, &optlen) == 0)
> +			stats->imissed += xdp_stats.rx_dropped;
>  
>  		stats->opackets += stats->q_opackets[i];
>  		stats->obytes += stats->q_obytes[i];
> @@ -1799,7 +1798,9 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
>  			AF_XDP_LOG(ERR, "Failed to probe %s\n", name);
>  			return -EINVAL;
>  		}
> +		/* TODO: reconnect socket from primary */
>  		eth_dev->dev_ops = &ops;
> +		eth_dev->device = &dev->device;
>  		rte_eth_dev_probing_finish(eth_dev);
>  		return 0;
>  	}
> 

Re: [dpdk-stable] [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process

[Loftus, Ciara]

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Stephen Hemminger
> Sent: Friday 3 September 2021 17:15
> To: dev@dpdk.org
> Cc: Stephen Hemminger <stephen@networkplumber.org>;
> stable@dpdk.org; xiaolong.ye@intel.com
> Subject: [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process
> 
> Doing basic operations like info_get or get_stats was broken
> in af_xdp PMD. The info_get would crash because dev->device
> was NULL in secondary process. Fix this by doing same initialization
> as af_packet and tap devices.
> 
> The get_stats would crash because the XDP socket is not open in
> primary process. As a workaround don't query kernel for dropped
> packets when called from secondary process.
> 
> Note: this does not address the other bug which is that transmitting
> in secondary process is broken because the send() in tx_kick
> will fail because XDP socket fd is not valid in secondary process.

Hi Stephen,

Apologies for the delayed reply, I was on vacation.

In the Bugzilla report you suggest we:
"mark AF_XDP as broken in with primary/secondary
and return an error in probe in secondary process".
I agree with this suggestion. However with this patch we still permit secondary, and just make sure it doesn't crash for get_stats. Did you change your mind?
Personally, I would prefer to have primary/secondary either working 100% or else not allowed at all by throwing an error during probe. What do you think? Do you have a reason/use case to permit secondary processes despite some features not being available eg. full stats, tx?

Thanks,
Ciara

> 
> Bugzilla ID: 805
> Fixes: f1debd77efaf ("net/af_xdp: introduce AF_XDP PMD")
> Cc: stable@dpdk.org
> Cc: xiaolong.ye@intel.com
> Ciara Loftus <ciara.loftus@intel.com>
> Qi Zhang <qi.z.zhang@intel.com>
> Anatoly Burakov <anatoly.burakov@intel.com>
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  drivers/net/af_xdp/rte_eth_af_xdp.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c
> b/drivers/net/af_xdp/rte_eth_af_xdp.c
> index 74ffa4511284..70abc14fa753 100644
> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -860,7 +860,7 @@ eth_stats_get(struct rte_eth_dev *dev, struct
> rte_eth_stats *stats)
>  	struct pkt_rx_queue *rxq;
>  	struct pkt_tx_queue *txq;
>  	socklen_t optlen;
> -	int i, ret;
> +	int i;
> 
>  	for (i = 0; i < dev->data->nb_rx_queues; i++) {
>  		optlen = sizeof(struct xdp_statistics);
> @@ -876,13 +876,12 @@ eth_stats_get(struct rte_eth_dev *dev, struct
> rte_eth_stats *stats)
>  		stats->ibytes += stats->q_ibytes[i];
>  		stats->imissed += rxq->stats.rx_dropped;
>  		stats->oerrors += txq->stats.tx_dropped;
> -		ret = getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
> -				XDP_STATISTICS, &xdp_stats, &optlen);
> -		if (ret != 0) {
> -			AF_XDP_LOG(ERR, "getsockopt() failed for
> XDP_STATISTICS.\n");
> -			return -1;
> -		}
> -		stats->imissed += xdp_stats.rx_dropped;
> +
> +		/* The socket fd is not valid in secondary process */
> +		if (rte_eal_process_type() != RTE_PROC_SECONDARY &&
> +		    getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
> +			       XDP_STATISTICS, &xdp_stats, &optlen) == 0)
> +			stats->imissed += xdp_stats.rx_dropped;
> 
>  		stats->opackets += stats->q_opackets[i];
>  		stats->obytes += stats->q_obytes[i];
> @@ -1799,7 +1798,9 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device
> *dev)
>  			AF_XDP_LOG(ERR, "Failed to probe %s\n", name);
>  			return -EINVAL;
>  		}
> +		/* TODO: reconnect socket from primary */
>  		eth_dev->dev_ops = &ops;
> +		eth_dev->device = &dev->device;
>  		rte_eth_dev_probing_finish(eth_dev);
>  		return 0;
>  	}
> --
> 2.30.2

Re: [dpdk-stable] [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process

[Stephen Hemminger]

On Mon, 20 Sep 2021 13:23:57 +0000
"Loftus, Ciara" <ciara.loftus@intel.com> wrote:

> > -----Original Message-----
> > From: dev <dev-bounces@dpdk.org> On Behalf Of Stephen Hemminger
> > Sent: Friday 3 September 2021 17:15
> > To: dev@dpdk.org
> > Cc: Stephen Hemminger <stephen@networkplumber.org>;
> > stable@dpdk.org; xiaolong.ye@intel.com
> > Subject: [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process
> > 
> > Doing basic operations like info_get or get_stats was broken
> > in af_xdp PMD. The info_get would crash because dev->device
> > was NULL in secondary process. Fix this by doing same initialization
> > as af_packet and tap devices.
> > 
> > The get_stats would crash because the XDP socket is not open in
> > primary process. As a workaround don't query kernel for dropped
> > packets when called from secondary process.
> > 
> > Note: this does not address the other bug which is that transmitting
> > in secondary process is broken because the send() in tx_kick
> > will fail because XDP socket fd is not valid in secondary process.  
> 
> Hi Stephen,
> 
> Apologies for the delayed reply, I was on vacation.
> 
> In the Bugzilla report you suggest we:
> "mark AF_XDP as broken in with primary/secondary
> and return an error in probe in secondary process".
> I agree with this suggestion. However with this patch we still permit secondary, and just make sure it doesn't crash for get_stats. Did you change your mind?
> Personally, I would prefer to have primary/secondary either working 100% or else not allowed at all by throwing an error during probe. What do you think? Do you have a reason/use case to permit secondary processes despite some features not being available eg. full stats, tx?
> 
> Thanks,
> Ciara

There are two cases where secondary is useful even if send/receive can't work from secondary process.
The pdump and proc-info applications can work with these patches.

I am using XDP over pdump as an easy way to get packets into the code for testing.

The flag in the documentation doesn't have a "limited" version.
If you want, will send another patch to disable secondary support.

Supporting secondary, means adding a mechanism to pass the socket around.

Re: [dpdk-stable] [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process

[Loftus, Ciara]

> 
> On Mon, 20 Sep 2021 13:23:57 +0000
> "Loftus, Ciara" <ciara.loftus@intel.com> wrote:
> 
> > > -----Original Message-----
> > > From: dev <dev-bounces@dpdk.org> On Behalf Of Stephen Hemminger
> > > Sent: Friday 3 September 2021 17:15
> > > To: dev@dpdk.org
> > > Cc: Stephen Hemminger <stephen@networkplumber.org>;
> > > stable@dpdk.org; xiaolong.ye@intel.com
> > > Subject: [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary
> process
> > >
> > > Doing basic operations like info_get or get_stats was broken
> > > in af_xdp PMD. The info_get would crash because dev->device
> > > was NULL in secondary process. Fix this by doing same initialization
> > > as af_packet and tap devices.
> > >
> > > The get_stats would crash because the XDP socket is not open in
> > > primary process. As a workaround don't query kernel for dropped
> > > packets when called from secondary process.
> > >
> > > Note: this does not address the other bug which is that transmitting
> > > in secondary process is broken because the send() in tx_kick
> > > will fail because XDP socket fd is not valid in secondary process.
> >
> > Hi Stephen,
> >
> > Apologies for the delayed reply, I was on vacation.
> >
> > In the Bugzilla report you suggest we:
> > "mark AF_XDP as broken in with primary/secondary
> > and return an error in probe in secondary process".
> > I agree with this suggestion. However with this patch we still permit
> secondary, and just make sure it doesn't crash for get_stats. Did you change
> your mind?
> > Personally, I would prefer to have primary/secondary either working 100%
> or else not allowed at all by throwing an error during probe. What do you
> think? Do you have a reason/use case to permit secondary processes despite
> some features not being available eg. full stats, tx?
> >
> > Thanks,
> > Ciara
> 
> There are two cases where secondary is useful even if send/receive can't
> work from secondary process.
> The pdump and proc-info applications can work with these patches.
> 
> I am using XDP over pdump as an easy way to get packets into the code for
> testing.
> 
> The flag in the documentation doesn't have a "limited" version.
> If you want, will send another patch to disable secondary support.

Thanks for explaining. Since there are use cases for secondary, even if the functionality is limited, I don't think it should be disabled.
Since we can't flag it as 'limited' in the feature matrix, could you please add a note about the send/receive limitation in the AF_XDP PMD documentation in a v2? There are already a number of limitations listed, which you can add to.

Thanks,
Ciara

> 
> Supporting secondary, means adding a mechanism to pass the socket
> around.

Re: [dpdk-stable] [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process

[Stephen Hemminger]

On Mon, 20 Sep 2021 15:09:36 +0000
"Loftus, Ciara" <ciara.loftus@intel.com> wrote:

> > 
> > On Mon, 20 Sep 2021 13:23:57 +0000
> > "Loftus, Ciara" <ciara.loftus@intel.com> wrote:
> >   
> > > > -----Original Message-----
> > > > From: dev <dev-bounces@dpdk.org> On Behalf Of Stephen Hemminger
> > > > Sent: Friday 3 September 2021 17:15
> > > > To: dev@dpdk.org
> > > > Cc: Stephen Hemminger <stephen@networkplumber.org>;
> > > > stable@dpdk.org; xiaolong.ye@intel.com
> > > > Subject: [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary  
> > process  
> > > >
> > > > Doing basic operations like info_get or get_stats was broken
> > > > in af_xdp PMD. The info_get would crash because dev->device
> > > > was NULL in secondary process. Fix this by doing same initialization
> > > > as af_packet and tap devices.
> > > >
> > > > The get_stats would crash because the XDP socket is not open in
> > > > primary process. As a workaround don't query kernel for dropped
> > > > packets when called from secondary process.
> > > >
> > > > Note: this does not address the other bug which is that transmitting
> > > > in secondary process is broken because the send() in tx_kick
> > > > will fail because XDP socket fd is not valid in secondary process.  
> > >
> > > Hi Stephen,
> > >
> > > Apologies for the delayed reply, I was on vacation.
> > >
> > > In the Bugzilla report you suggest we:
> > > "mark AF_XDP as broken in with primary/secondary
> > > and return an error in probe in secondary process".
> > > I agree with this suggestion. However with this patch we still permit  
> > secondary, and just make sure it doesn't crash for get_stats. Did you change
> > your mind?  
> > > Personally, I would prefer to have primary/secondary either working 100%  
> > or else not allowed at all by throwing an error during probe. What do you
> > think? Do you have a reason/use case to permit secondary processes despite
> > some features not being available eg. full stats, tx?  
> > >
> > > Thanks,
> > > Ciara  
> > 
> > There are two cases where secondary is useful even if send/receive can't
> > work from secondary process.
> > The pdump and proc-info applications can work with these patches.
> > 
> > I am using XDP over pdump as an easy way to get packets into the code for
> > testing.
> > 
> > The flag in the documentation doesn't have a "limited" version.
> > If you want, will send another patch to disable secondary support.  
> 
> Thanks for explaining. Since there are use cases for secondary, even if the functionality is limited, I don't think it should be disabled.
> Since we can't flag it as 'limited' in the feature matrix, could you please add a note about the send/receive limitation in the AF_XDP PMD documentation in a v2? There are already a number of limitations listed, which you can add to.
> 
> Thanks,
> Ciara
> 
> > 
> > Supporting secondary, means adding a mechanism to pass the socket
> > around.  

Looking at this in more detail, and my recommendation is:
For 21.11 release (and mark it as Fixes so it gets backported). Have the driver
return -ENOTSUP in secondary process.

For 22.03 add real secondary support using the rte_mp_msg to pass necessary
state to secondary process. Includes socket (and other memory regions?).

The pdump and proc-info cases are only useful for developer testing, and there are
other ways to do the same thing.

Re: [dpdk-stable] [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process

[Loftus, Ciara]

> > > > >
> > > > > Doing basic operations like info_get or get_stats was broken
> > > > > in af_xdp PMD. The info_get would crash because dev->device
> > > > > was NULL in secondary process. Fix this by doing same initialization
> > > > > as af_packet and tap devices.
> > > > >
> > > > > The get_stats would crash because the XDP socket is not open in
> > > > > primary process. As a workaround don't query kernel for dropped
> > > > > packets when called from secondary process.
> > > > >
> > > > > Note: this does not address the other bug which is that transmitting
> > > > > in secondary process is broken because the send() in tx_kick
> > > > > will fail because XDP socket fd is not valid in secondary process.
> > > >
> > > > Hi Stephen,
> > > >
> > > > Apologies for the delayed reply, I was on vacation.
> > > >
> > > > In the Bugzilla report you suggest we:
> > > > "mark AF_XDP as broken in with primary/secondary
> > > > and return an error in probe in secondary process".
> > > > I agree with this suggestion. However with this patch we still permit
> > > secondary, and just make sure it doesn't crash for get_stats. Did you
> change
> > > your mind?
> > > > Personally, I would prefer to have primary/secondary either working
> 100%
> > > or else not allowed at all by throwing an error during probe. What do you
> > > think? Do you have a reason/use case to permit secondary processes
> despite
> > > some features not being available eg. full stats, tx?
> > > >
> > > > Thanks,
> > > > Ciara
> > >
> > > There are two cases where secondary is useful even if send/receive can't
> > > work from secondary process.
> > > The pdump and proc-info applications can work with these patches.
> > >
> > > I am using XDP over pdump as an easy way to get packets into the code
> for
> > > testing.
> > >
> > > The flag in the documentation doesn't have a "limited" version.
> > > If you want, will send another patch to disable secondary support.
> >
> > Thanks for explaining. Since there are use cases for secondary, even if the
> functionality is limited, I don't think it should be disabled.
> > Since we can't flag it as 'limited' in the feature matrix, could you please add
> a note about the send/receive limitation in the AF_XDP PMD documentation
> in a v2? There are already a number of limitations listed, which you can add
> to.
> >
> > Thanks,
> > Ciara
> >
> > >
> > > Supporting secondary, means adding a mechanism to pass the socket
> > > around.
> 
> Looking at this in more detail, and my recommendation is:
> For 21.11 release (and mark it as Fixes so it gets backported). Have the driver
> return -ENOTSUP in secondary process.
> 
> For 22.03 add real secondary support using the rte_mp_msg to pass
> necessary
> state to secondary process. Includes socket (and other memory regions?).
> 
> The pdump and proc-info cases are only useful for developer testing, and
> there are
> other ways to do the same thing.


+1 that sounds reasonable to me.

Thanks,
Ciara

Re: [dpdk-stable] [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process

[Ferruh Yigit]

On 9/23/2021 1:33 PM, Loftus, Ciara wrote:
>>>>>>
>>>>>> Doing basic operations like info_get or get_stats was broken
>>>>>> in af_xdp PMD. The info_get would crash because dev->device
>>>>>> was NULL in secondary process. Fix this by doing same initialization
>>>>>> as af_packet and tap devices.
>>>>>>
>>>>>> The get_stats would crash because the XDP socket is not open in
>>>>>> primary process. As a workaround don't query kernel for dropped
>>>>>> packets when called from secondary process.
>>>>>>
>>>>>> Note: this does not address the other bug which is that transmitting
>>>>>> in secondary process is broken because the send() in tx_kick
>>>>>> will fail because XDP socket fd is not valid in secondary process.
>>>>>
>>>>> Hi Stephen,
>>>>>
>>>>> Apologies for the delayed reply, I was on vacation.
>>>>>
>>>>> In the Bugzilla report you suggest we:
>>>>> "mark AF_XDP as broken in with primary/secondary
>>>>> and return an error in probe in secondary process".
>>>>> I agree with this suggestion. However with this patch we still permit
>>>> secondary, and just make sure it doesn't crash for get_stats. Did you
>> change
>>>> your mind?
>>>>> Personally, I would prefer to have primary/secondary either working
>> 100%
>>>> or else not allowed at all by throwing an error during probe. What do you
>>>> think? Do you have a reason/use case to permit secondary processes
>> despite
>>>> some features not being available eg. full stats, tx?
>>>>>
>>>>> Thanks,
>>>>> Ciara
>>>>
>>>> There are two cases where secondary is useful even if send/receive can't
>>>> work from secondary process.
>>>> The pdump and proc-info applications can work with these patches.
>>>>
>>>> I am using XDP over pdump as an easy way to get packets into the code
>> for
>>>> testing.
>>>>
>>>> The flag in the documentation doesn't have a "limited" version.
>>>> If you want, will send another patch to disable secondary support.
>>>
>>> Thanks for explaining. Since there are use cases for secondary, even if the
>> functionality is limited, I don't think it should be disabled.
>>> Since we can't flag it as 'limited' in the feature matrix, could you please add
>> a note about the send/receive limitation in the AF_XDP PMD documentation
>> in a v2? There are already a number of limitations listed, which you can add
>> to.
>>>
>>> Thanks,
>>> Ciara
>>>
>>>>
>>>> Supporting secondary, means adding a mechanism to pass the socket
>>>> around.
>>
>> Looking at this in more detail, and my recommendation is:
>> For 21.11 release (and mark it as Fixes so it gets backported). Have the driver
>> return -ENOTSUP in secondary process.
>>
>> For 22.03 add real secondary support using the rte_mp_msg to pass
>> necessary
>> state to secondary process. Includes socket (and other memory regions?).
>>
>> The pdump and proc-info cases are only useful for developer testing, and
>> there are
>> other ways to do the same thing.
> 
> 
> +1 that sounds reasonable to me.
> 

This patch superseded by following which disables the secondary process support:
https://patches.dpdk.org/project/dpdk/patch/20210930134604.32585-1-ciara.loftus@intel.com/