some problem about netmap

[mstian88]

./pkt-gen -i eth1 -f rx -X
the print info shows slot->len is 2048?  why?
the packets was sended with tcpreplay.
when Multiple packets len is 1514, pkt-gen receive avial >1,  the slot->len is 2048


like this:
[2213]:slotlen[1514],curidx[189],bufidx[24767],avail[3],iwhile[475],ifor[16],buf_ofs[5603328],rings[32]  
[2214]:slotlen[2048],curidx[190],bufidx[24768],avail[2],iwhile[475],ifor[16],buf_ofs[5603328],rings[32]  
[2215]:slotlen[926],curidx[191],bufidx[24769],avail[1],iwhile[475],ifor[16],buf_ofs[5603328],rings[32]  
[2216]:slotlen[1514],curidx[192],bufidx[24770],avail[1],iwhile[476],ifor[16],buf_ofs[5603328],rings[32]