netdev - RE: [net-next PATCH 1/1] e1000e: Expose MDI-X state via sysfs

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Date:	Tue, 19 May 2009 16:45:28 -0700
From:	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
To:	Chaitanya Lala <clala@...erbed.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
CC:	"jgarzik@...hat.com" <jgarzik@...hat.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [net-next PATCH 1/1] e1000e: Expose MDI-X state via sysfs

Chaitanya Lala wrote:
> Jeff Kirsher wrote:
>> On Tue, May 19, 2009 at 2:05 PM, Chaitanya Lala <clala@...erbed.com>
>> wrote:
>>
>>> While debugging network connectivity problems, it is often helpful
>>> to report the MDI-X state. The is_mdix variable holds the current
>>> state which we expose on a per-interface basis as a sysfs attribute.
>>> We use sysfs over methods such as netlink due to the convenience of
>>> reading a file (using the cat command) as opposed to connecting to a
>>> netlink socket. If we use a fiber PHY then is_mdix will always be
>>> zero
>>> as the mdi-x feature only applies to copper PHYs.
>>>
>>> Signed-off-by: Chaitanya Lala <clala@...erbed.com>
>>> Signed-off-by: Arthur Jones <ajones@...erbed.com>
>>> ---
>>>
>>
>> NAK.  We do not want to be adding sysfs entries for every little
>> piece
>> of information in the driver.  Instead, I would suggest looking at
>> enhancing existing tools like ethtool to get that sort of information
>> in a more generic way which is not driver specific.
>>
>>
> The MDI-X setting is a non-standard piece of information & every
> driver may or may-not have it. But still this is an important
> de-bugging tool & we would want to use this information from the
> drivers that do provide this facility.  So what would be a standard
> way to do this via something like ethtool ? Any pointers would be
> helpful.

how about (psuedo diff)

        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
+       MDI-X: on
        Supports Wake-on: umbg
        Wake-on: g
        Current message level: 0x00000003 (3)
        Link detected: yes

where possible MDI-X values are (on|off)

This way drivers can optionally implement the feature in their 
get_settings and set_settings handlers.

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