DPDK Pdump tool is not able to attach to DPDK test pmd primary application

DPDK Pdump tool is not able to attach to DPDK test pmd primary application

[Sameer Vaze]

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Hey Folks,

I see the following message when I attempt to attach pdump to the testpmd sample application:

Pdump output:
EAL: Failed to hotplug add device
EAL: Error - exiting with code: 1
  Cause: vdev creation failed:create_mp_ring_vdev:695

Testpmd output:
Reached maximum number of Ethernet ports
EAL: Driver cannot attach the device (net_pcap_rx_0)
EAL: Failed to hotplug add device on primary

The primary and secondary applications were run using the following commands:

Primary: sudo ./dpdk-testpmd --proc-type=primary --file-prefix=test -d /path/to/pmd
Secondary: sudo ./dpdk-pdump --proc-type=secondary --file-prefix=test -d /path/to/pmd -- --pdump 'port=0,queue=1,rx-dev=./rx.pcap,tx-dev=./tx.pcap'

DPDK version: 22.11.1

Is this a known issue? Is there any known fix for this?

Thanks
Sameer Vaze

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Re: DPDK Pdump tool is not able to attach to DPDK test pmd primary application

[Stephen Hemminger]

On Wed, 14 Feb 2024 22:44:46 +0000
Sameer Vaze <svaze@qti.qualcomm.com> wrote:

> Hey Folks,
> 
> I see the following message when I attempt to attach pdump to the testpmd sample application:
> 
> Pdump output:
> EAL: Failed to hotplug add device
> EAL: Error - exiting with code: 1
>   Cause: vdev creation failed:create_mp_ring_vdev:695
> 
> Testpmd output:
> Reached maximum number of Ethernet ports
> EAL: Driver cannot attach the device (net_pcap_rx_0)
> EAL: Failed to hotplug add device on primary
> 
> The primary and secondary applications were run using the following commands:
> 
> Primary: sudo ./dpdk-testpmd --proc-type=primary --file-prefix=test -d /path/to/pmd
> Secondary: sudo ./dpdk-pdump --proc-type=secondary --file-prefix=test -d /path/to/pmd -- --pdump 'port=0,queue=1,rx-dev=./rx.pcap,tx-dev=./tx.pcap'
> 
> DPDK version: 22.11.1
> 
> Is this a known issue? Is there any known fix for this?
> 
> Thanks
> Sameer Vaze

pdump and dumpcap can't work where the actual data transmit/receive is done in secondary
process. The problem is in the design using callbacks and the way the pdump/dumpcap is
initialized.

The pdump/dumpcap works as an additional secondary process.
At startup pdump/dumpcap communicates with primary process to enable callbacks on rx/tx but
these work only in the primary process. In secondary process, there are no rx/tx callbacks.

RE: DPDK Pdump tool is not able to attach to DPDK test pmd primary application

[Sameer Vaze]

I don't think the pdump application is doing the transmit/receive. Am I missing something in the command line arguments I passed below that would configure it to transmit/receive?

Passing in the rx-dev and tx-dev as pcap should not cause that right? The documentation mentions those as mandatory arguments. I tried specifying an interface as well and saw the same issue.

Thanks
Sameer Vaze
-----Original Message-----
From: Stephen Hemminger <stephen@networkplumber.org> 
Sent: Saturday, February 17, 2024 10:00 AM
To: Sameer Vaze <svaze@qti.qualcomm.com>
Cc: users@dpdk.org
Subject: Re: DPDK Pdump tool is not able to attach to DPDK test pmd primary application

WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.

On Wed, 14 Feb 2024 22:44:46 +0000
Sameer Vaze <svaze@qti.qualcomm.com> wrote:

> Hey Folks,
>
> I see the following message when I attempt to attach pdump to the testpmd sample application:
>
> Pdump output:
> EAL: Failed to hotplug add device
> EAL: Error - exiting with code: 1
>   Cause: vdev creation failed:create_mp_ring_vdev:695
>
> Testpmd output:
> Reached maximum number of Ethernet ports
> EAL: Driver cannot attach the device (net_pcap_rx_0)
> EAL: Failed to hotplug add device on primary
>
> The primary and secondary applications were run using the following commands:
>
> Primary: sudo ./dpdk-testpmd --proc-type=primary --file-prefix=test -d 
> /path/to/pmd
> Secondary: sudo ./dpdk-pdump --proc-type=secondary --file-prefix=test -d /path/to/pmd -- --pdump 'port=0,queue=1,rx-dev=./rx.pcap,tx-dev=./tx.pcap'
>
> DPDK version: 22.11.1
>
> Is this a known issue? Is there any known fix for this?
>
> Thanks
> Sameer Vaze

pdump and dumpcap can't work where the actual data transmit/receive is done in secondary process. The problem is in the design using callbacks and the way the pdump/dumpcap is initialized.

The pdump/dumpcap works as an additional secondary process.
At startup pdump/dumpcap communicates with primary process to enable callbacks on rx/tx but these work only in the primary process. In secondary process, there are no rx/tx callbacks.

Re: DPDK Pdump tool is not able to attach to DPDK test pmd primary application

[Stephen Hemminger]

On Thu, 22 Feb 2024 19:27:01 +0000
Sameer Vaze <svaze@qti.qualcomm.com> wrote:

> I don't think the pdump application is doing the transmit/receive. Am I missing something in the command line arguments I passed below that would configure it to transmit/receive?
> 
> Passing in the rx-dev and tx-dev as pcap should not cause that right? The documentation mentions those as mandatory arguments. I tried specifying an interface as well and saw the same issue.
> 
> Thanks

The issue arises if send/receive is done in a secondary process as in:

1. Primary process
2. Secondary process that does send/receive
3. Pdump application (secondary)

If #2 does send/receive it will not be seen by #3