Question about dpdk-pdump ring buffer

[sakaia at fujitsu.com]

Question about dpdk-pdump ring buffer

With updating from 21.08 to 21.11, The packet capture is failed. 
Previously(21.08) it works fine.

I want to know 2 things
a)the difference of dpdk-pdump between 21.08 and 21.11 (seems bpf changes) 
b)where pcap capture the ring buffer for secondary process?

The output is coming from print_pdump_stats function is zero for 3 parameters.(N.B.1) 
Above parameters are counted on pdump_rxtx function.(it is zero on this function also) 
The ring seems copied under mp_handle (process_msg) or mp_pdump.

P.S.
I understand dpdk-pdump seems to be deprecated by introducing dpdk-dumpcap.

Reference
  https://doc.dpdk.org/guides/prog_guide/pdump_lib.html
  https://doc.dpdk.org/guides/prog_guide/multi_proc_support.html

N.B.1

##### PDUMP DEBUG STATS #####
 -packets dequeued:                     0
 -packets transmitted to vdev:          0
 -packets freed:                        0

Thanks in advance

Atsushi SAKAI