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From: Clarylin L <clearasu@gmail.com>
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Subject: [dpdk-dev]  Unable to get multi-segment mbuf working for ixgbe
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Hello,

I am trying to use multi-segment mbuf to receive large packet. I enabled
jumbo_frame and enable_scatter for the port and was expecting mbuf chaining
would be used to receive packets larger than the mbuf size (which was set
to 2048).

When sending 3000-byte (without fragmentation) packet from another non-dpdk
host, I didn't see packet was received by the ixgbe PMD driver.

After a quick debugging session I found that the following statement
in ixgbe_recv_scattered_pkts
(ixgbe_rxtx.c) is
always true and break the loop in case of large packet, while it's not the
case for small packet (smaller than mbuf size):

if (! staterr & rte_cpu_to_le32(IXGBE_RXDADV_STAT_DD))
    break;

Is enabling jumbo_frame and enable_scatter good enough to get started the
mbuf chaining?

Appreciate any input! Thanks.