netdev - Re: (Lack of) specification for RX n-tuple filtering

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Message-ID: <1291890687.24019.29.camel@lb-tlvb-vladz>
Date:	Thu, 9 Dec 2010 12:31:27 +0200
From:	"Vladislav Zolotarov" <vladz@...adcom.com>
To:	"Ben Hutchings" <bhutchings@...arflare.com>
cc:	"David Miller" <davem@...emloft.net>,
	"dm@...lsio.com" <dm@...lsio.com>,
	"peter.p.waskiewicz.jr@...el.com" <peter.p.waskiewicz.jr@...el.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: (Lack of) specification for RX n-tuple filtering

> > It's not the same, this whole ordering thing you expect in netfilter
> > land is simply not present in these hardware implementations.
> > 
> > The hardware does a parallel TCAM match lookup, and whatever matches
> > is used.
> 
> I think the match with the lowest index wins, which is why it's possible
> to specify the rule's index (location) with ETHTOOL_SRXCLSRLINS and why
> Peter defined new commands without that for use with the ixgbe driver.
> 

Ben, practically, with the current ethtool userspace implementation it
seems like there is no way to specify the CAM index of the rule in the
n-tuple interface, is it? So, the decision on the index is up to the
vendor thus creating an uncertainty space. 

And I guess it's exactly what Dimitris meant talking about the index -
he said "a rule index", u say "a CAM index" while generally we are
talking about the same thing. U r referring the ETHTOOL_SRXCLSRLINS but
it has no user space interface yet and it's unclear when it will, while
n-tuple is already there. We can't remove the existing user space
interfaces - I agree. Then let's not adding the interfaces interfering
with the existing ones. This immediately implies that
ETHTOOL_SRXCLSRLINS shell never see light in a userland as a separate
interface and n-tuple user interface should be properly extended to
implement the missing ETHTOOL_SRXCLSRLINS functionality.

Pls., comment.

thanks,
vlad

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