[Intel-wired-lan] [E1000-devel] i40e card Tx resets

Sowmini Varadhan sowmini.varadhan at oracle.com
Thu Mar 17 19:41:17 UTC 2016

On (03/17/16 12:28), Jesse Brandeburg wrote:
> We can ask on netdev if the driver should defend against this kind of
> input to hard_start_xmit (transmit routine), but the driver doesn't
> check the maximum length of the skb to see if it is invalid, because
> the stack can never build (only pktgen can) these invalid SKBs.
> The issue is that pktgen builds skb->data with a contiguous buffer of
> whatever size transmit requested, (regardless of MTU) and then sends it
> straight to the transmit routine, no segmentation flags, no MSS set.

I see. And after you mentioned it, I checked with ixgbe, sure 
enough, that also results in a tx-hang for the pktgen test case
(whereas there were no issues with the (rds-stress , ixgbe) test.

I would surmise that pktgen is a bit of an outlier, more interesting
to focus on those cases that use the regular stack.

I dont know if dpdk can create the same issues as pktgen?

> we don't need to bring it up on netdev.  We have a way to troubleshoot
> MDDs that I can send to you, if you want to do the work.  Otherwise we
> need to have some time to reproduce here.

yes, I can do the work, since I already have this nicely set up.
Just need some hings on how to trouble-shoot the mdd.


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