linking host descriptors issues

yingchun li1

I'm using a XTCIEVMK2X EVM. There is an issue about NETCP&Multicore Navigator

I try to send network data to Gigabit Ethernet (GbE) Switch Subsystem from host using linked host descriptors. See the hint below:

A->B->C->NULL

A,B,C is the descriptors poped from poll queue, and the "Packet Return Queue" field of A,B,C is filled with the Return Queue number. And the header A is pushed to the send queue.

The data(sum of A, B,C) can out put from GbE Switch correctly(I can captured the package in the wire) but I can only see the descriptor A freed in the Return Queue. The B and C is missed. What could be the problem?

Thanks very much!

over 12 years ago

0 Alberto Chessa over 12 years ago

Mastermind 6670 points

Hi,

Have you set the return policy in the A host descriptor?

Word 2 Bit 15: Return Policy:

This field indicates the return policy for this packet.
0 = Entire packet (still linked together) should be returned to queue specified in bits 13-0 below.
1 = Each buffer should be returned to queue specified in bits 13-0 of Word 2 in their respective
descriptors. The Tx DMA will return each buffer in sequence

0 yingchun li1 over 12 years ago in reply to Alberto Chessa

Prodigy 80 points

Hi Alberto

Yes, it is the root cause. I can fix my problem after I set this bit. Thanks very much!

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linking host descriptors issues