netdev - RE: [PATCH] bnx2: turn off the network statck during initialization

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Message-ID: <1345152321.2832.17.camel@bwh-desktop.uk.solarflarecom.com>
Date:	Thu, 16 Aug 2012 22:25:21 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Jiang Wang <Jiang.Wang@...erbed.com>
CC:	Michael Chan <mchan@...adcom.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Chaitanya Lala <Chaitanya.Lala@...erbed.com>,
	"Francis St. Amant" <Francis.St.Amant@...erbed.com>
Subject: RE: [PATCH] bnx2: turn off the network statck during initialization

On Thu, 2012-08-16 at 20:28 +0000, Jiang Wang wrote:
[...]
> Also, I have another comment related to link state.
> 
> Right now, the bnx2 driver powers up the device in bnx2_init_board(),
> regardless the netif_carrier is on or off. This may introduce
> following inconsistent behaviors:
> 1) suppose the cable is plugged in to the NIC and the other end is
> connected to a switch
> 2) user powers up the box
> 3) the Linux does not bring up the interface; i.e, ifconfig ethx shows
> it is down

Most distributions will bring up all interfaces at boot, by default.

> 4) ethtool ethx will show no link
> 5) if the user goes to check the light on the physical NIC, he will
> see the green link light is ON. That means the link is up, right? 
> 
> I think it is better to power down the device until bnx2_open is
> called. In this way, ethtool report and the physical link light will
> be consistent. 
[...]

In general, a physical network interface may need to be enabled to allow
management traffic to a BMC, even when the interface is in the 'down'
state on the host.

The link state should be considered unknown whenever the interface is
down, and /sys/class/net/$IFACE/carrier is not readable then.  However
ETHTOOL_GLINK is not expected to fail in this way, and must always
return 0 (down) or 1 (up).  The convention (which is now enforced in
ethtool_get_link()) is that when the interface is down it should always
return 0.

Ben.

-- 
Ben Hutchings, Staff 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.

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