enable tcpdump GUESS_TSO flag?

[Eggert, Lars]

Hi,

On Apr 8, 2013, at 7:18, YongHyeon PYUN <pyunyh at gmail.com> wrote:
> I don't have strong option on enabling that flag but I think it
> would be even better to have an option to enable/disable that
> feature(default off).

I agree that would be the better solution, but it's a larger patch to the source.

> em(4) controllers require IP length should
> be 0 before controller performs TSO operation. fxp(4) controllers
> requires IP length should be set to the IP length of the first TCP
> segment after TSO operation. bpf listeners see the modified packet
> so it can confuse them. AFAIK, except em(4)/fxp(4) controllers, no
> other controllers in tree have such limitation with TSO. Enabling
> GUESS_TSO flag may make it hard to debug network/driver issues I
> guess.

Not sure. Yeah, you wouldn't see "IP bad-len 0" messages anymore in traces, but instead those packets would contain garbage. That should still be noticeable to someone looking into the dump.

Lars