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From: Ben Hutchings <bhutchings@solarflare.com>
To: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: [PATCH] ethtool: ETHTOOL_SFEATURES: remove NETIF_F_COMPAT return
Date: Sat, 28 May 2011 00:25:55 +0100	[thread overview]
Message-ID: <1306538755.2759.31.camel@bwh-desktop> (raw)
In-Reply-To: <20110527163409.GA8497@rere.qmqm.pl>

On Fri, 2011-05-27 at 18:34 +0200, Michał Mirosław wrote:
> On Fri, May 27, 2011 at 04:45:50PM +0100, Ben Hutchings wrote:
> > On Fri, 2011-05-27 at 17:28 +0200, Michał Mirosław wrote:
[...]
> > >      (note: ETHTOOL_S{SG,...} are not ever going away)
> > >    - causes NETIF_F_* to be an ABI
> > If feature flag numbers are not stable then what is the point of
> > /sys/class/net/<name>/features?  Also, I'm not aware that features have
> > ever been renumbered in the past.
> 
> Since no NETIF_F_* were exported earlier, I assume /sys/class/net/*/features
> is a debugging aid. What is it used for besides that?

xen-api <https://github.com/xen-org/xen-api> uses it in
scripts/InterfaceReconfigureVswitch.py.  Though it doesn't seem to be
used for a particularly good reason...

> [...]
> > > Both versions are rough at the edges, but working. Both assume that no
> > > behaviour changes are to be made for old '-K' options.
> > No, my changes are intended to enhance the old options.
> 
> Kernel side already enhances them to not forget other features
> 'wanted' state. What other enhancements are on your mind?

So it does; for some reason I didn't realise that.  Then I suppose there
isn't a benefit from using ETHTOOL_SFEATURES for existing feature flags.

> BTW, I just recalled that ETHTOOL_F_WISH is set only as an information
> about bits in features[].valid masks. So zero return does not mean, that
> other features (not in .valid masks) haven't changed.

That was already true.

> This means that
> userspace needs to reread features after any SFEATURES call, not just
> those returning non-zero.

Not necessarily, though of course it is helpful to report consequential
feature changes.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.


  reply	other threads:[~2011-05-27 23:25 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-14  1:05 [PATCH net-2.6] ethtool: Remove fallback to old ethtool operations for ETHTOOL_SFEATURES Ben Hutchings
2011-05-14  9:54 ` Michał Mirosław
2011-05-14 20:08   ` Ben Hutchings
2011-05-14 10:31 ` [PATCH] net: fix ETHTOOL_SFEATURES compatibility with old ethtool_ops.set_flags Michał Mirosław
2011-05-14 10:35 ` [PATCH net-2.6] ethtool: Remove fallback to old ethtool operations for ETHTOOL_SFEATURES Michał Mirosław
2011-05-16  2:45   ` Ben Hutchings
2011-05-16 12:13     ` Michał Mirosław
2011-05-16 13:28     ` [PATCH] ethtool: ETHTOOL_SFEATURES: remove NETIF_F_COMPAT return Michał Mirosław
2011-05-16 13:37       ` Ben Hutchings
2011-05-16 14:23         ` Michał Mirosław
2011-05-16 14:53           ` Ben Hutchings
2011-05-16 15:01             ` Michał Mirosław
2011-05-16 15:57               ` [RFC PATCH ethtool 1/3] ethtool: Regularise offload feature settings Ben Hutchings
2011-05-16 15:57               ` [RFC PATCH ethtool 2/3] ethtool: Report any consequential offload feature changes Ben Hutchings
2011-05-16 15:58               ` [RFC PATCH ethtool 3/3] ethtool: Use ETHTOOL_{G,S}FEATURES where available Ben Hutchings
2011-05-16 20:51             ` [PATCH] ethtool: ETHTOOL_SFEATURES: remove NETIF_F_COMPAT return Michał Mirosław
2011-05-16 21:08               ` Ben Hutchings
2011-05-16 21:50                 ` Michał Mirosław
2011-05-16 22:09                   ` Ben Hutchings
2011-05-17  8:45                     ` Michał Mirosław
2011-05-17 20:33                     ` [RFC PATCH ethtool] ethtool: merge ETHTOOL_[GS]FEATURES support to -k/-K modes Michał Mirosław
2011-05-18 19:02                     ` [PATCH] ethtool: ETHTOOL_SFEATURES: remove NETIF_F_COMPAT return Ben Hutchings
2011-05-19  9:18                       ` Michał Mirosław
2011-05-19 13:25                         ` [RFC PATCH v3 ethtool] ethtool: implement [GS]FEATURES calls Michał Mirosław
2011-05-16 20:54             ` [RFC PATCH ethtool] ethtool: implement G/SFEATURES calls Michał Mirosław
2011-05-16 18:09           ` [PATCH] ethtool: ETHTOOL_SFEATURES: remove NETIF_F_COMPAT return David Miller
2011-05-19 10:03             ` Michał Mirosław
2011-05-24  9:14               ` Michał Mirosław
2011-05-24 19:39                 ` David Miller
2011-05-24 21:59                   ` Michał Mirosław
2011-05-27 14:13                     ` Ben Hutchings
2011-05-27 15:28                       ` Michał Mirosław
2011-05-27 15:45                         ` Ben Hutchings
2011-05-27 16:34                           ` Michał Mirosław
2011-05-27 23:25                             ` Ben Hutchings [this message]
2011-05-28  7:35                               ` Michał Mirosław
     [not found]                                 ` <20110528073525.GA19033-CoA6ZxLDdyEEUmgCuDUIdw@public.gmane.org>
2011-05-28 10:07                                   ` [Xen-devel] " Ian Campbell
     [not found]                                     ` <1306577228.23577.17.camel-ztPmHsLffjjnO4AKDKe2m+kiAK3p4hvP@public.gmane.org>
2011-05-28 17:31                                       ` Jesse Gross
     [not found]                                         ` <BANLkTime8PHYe+BFELt92gg7SZ91xKvAwA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-29  9:38                                           ` Michał Mirosław
     [not found]                                             ` <20110529093849.GA5245-CoA6ZxLDdyEEUmgCuDUIdw@public.gmane.org>
2011-05-31 18:43                                               ` Jesse Gross
2011-05-26 10:42                   ` [RESEND PATCH net] net: fix ETHTOOL_SFEATURES compatibility with old ethtool_ops.set_flags Michał Mirosław
2011-05-26 18:14                     ` David Miller
2011-05-14 10:41 ` [PATCH v2] " Michał Mirosław

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