From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH] app/testpmd: do not enable Rx offloads by
	default
Date: Fri, 26 Jan 2018 08:48:11 +0100
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Cc: Moti Haimovsky <motih@mellanox.com>, dev@dpdk.org,
 "shahafs@mellanox.com" <shahafs@mellanox.com>, "Yigit,
 Ferruh" <ferruh.yigit@intel.com>
To: "Lu, Wenzhuo" <wenzhuo.lu@intel.com>
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26/01/2018 08:30, Lu, Wenzhuo:
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > 25/01/2018 02:11, Lu, Wenzhuo:
> > > > --- a/app/test-pmd/testpmd.c
> > > > +++ b/app/test-pmd/testpmd.c
> > > > @@ -305,9 +305,7 @@ struct fwd_engine * fwd_engines[] = {
> > > >   */
> > > >  struct rte_eth_rxmode rx_mode = {
> > > >  	.max_rx_pkt_len = ETHER_MAX_LEN, /**< Default maximum frame
> > > > length. */
> > > > -	.offloads = (DEV_RX_OFFLOAD_VLAN_FILTER |
> > > > -		     DEV_RX_OFFLOAD_VLAN_STRIP |
> > > > -		     DEV_RX_OFFLOAD_CRC_STRIP),
> > > > +	.offloads = 0,
> > >
> > > Change the default behavior may trigger other problems. I think TX offload
> > could be a good reference. Get the capability and check what's supported
> > first, then ignore the not supported functions with printing a warning but
> > not block anything...
> > 
> > I agree that we should check the capabilities before requesting an offload.
> > But I disagree on another point: we should not enable an offload if the user
> > did not request it explicitly. It makes things unclear.
> > This is a testing tool, it should be close to the ethdev API behavior.
> > 
> > Why these offload flags are silently enabled?
> 
> I don't think it's silently. It's a global configuration. In this case, testpmd is the user, it does request it explicitly. If it's not so explicit, maybe we can consider moving all the configuration to a specific configure file.
> Talking about why it's enabled by default. Hard to figure out the history. To my opinion, the original designer wants to simulate the common case.

Please do not justify a design mistake by history.

This is a test tool, so we don't care about the common case.
A test tool should not try to guess the best configuration.
Only the user should decide the configuration to apply,
and the default should be empty, as the API is.