Re: [RFC] ethtool: Expand ethtool_cmd.speed to 32 bits

[David Miller <davem@davemloft.net>]

From: Brandon Philips <brandon@ifup.org>
Date: Tue, 15 Jul 2008 23:47:09 -0700

> On 15:27 Tue 15 Jul 2008, David Miller wrote:
> > From: Rick Jones <rick.jones2@hp.com>
> > Date: Tue, 15 Jul 2008 14:53:16 -0700
> > 
> > > Brandon Philips wrote:
> > > > Introduce the speed_hi field to ethtool_cmd, using the reserved space,
> > > > to expand the speed field to 2^32 Megabits/second.
> > > > 
> > > > Making this field expansion now gives us plenty of time to fix up the
> > > > user-space pieces that use SIOCETHTOOL before hardware faster than 64
> > > > Gb/s is available.
> > > > 
> > > > Signed-off-by: Brandon Philips <bphilips@suse.de>
> > > > 
> > > > ---
> > > >  include/linux/ethtool.h |   17 ++++++++++++++++-
> > > >  1 file changed, 16 insertions(+), 1 deletion(-)
> > > > 
> > > > Index: linux-2.6/include/linux/ethtool.h
> > > > ===================================================================
> > > > --- linux-2.6.orig/include/linux/ethtool.h
> > > > +++ linux-2.6/include/linux/ethtool.h
> > > > @@ -27,9 +27,24 @@ struct ethtool_cmd {
> > > >  	__u8	autoneg;	/* Enable or disable autonegotiation */
> > > >  	__u32	maxtxpkt;	/* Tx pkts before generating tx int */
> > > >  	__u32	maxrxpkt;	/* Rx pkts before generating rx int */
> > > > -	__u32	reserved[4];
> > > > +	__u16	speed_hi;
> > > > +	__u16	reserved2;
> > > > +	__u32	reserved[3];
> > > >  };
> > > 
> > > I certainly agree with the concept of preparing for faster NICs.  Are 
> > > bits in that structure sufficiently precious to go the split route, or 
> > > would it be cleaner to just grab a contiguous 32 bits from the structure?
> > 
> > That's less space we can use to make similar expansions.
> > 
> > And we have to keep the existing u16 chunk there anyways, because existing
> > applications are only going to provide that part.
> 
> Agreed.  Can this be queued for 2.6.27 then?

Jeff?