netdev - Re: [PATCH net-next v3] rocker: add debugfs support to dump internal tables

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Message-ID: <20160317202519.GA30210@lunn.ch>
Date:	Thu, 17 Mar 2016 21:25:19 +0100
From:	Andrew Lunn <andrew@...n.ch>
To:	Murali Karicheri <m-karicheri2@...com>
Cc:	David Miller <davem@...emloft.net>, sfeldma@...il.com,
	netdev@...r.kernel.org, jiri@...nulli.us
Subject: Re: [PATCH net-next v3] rocker: add debugfs support to dump internal
 tables

On Thu, Mar 17, 2016 at 04:10:31PM -0400, Murali Karicheri wrote:
> David,
> 
> On 08/18/2015 04:47 PM, David Miller wrote:
> > I see some drivers where the foo_debugfs.c file is larger than the rest
> > of the driver.  Once people start using it, it's like crack, and they
> > dump every single debugging widget they found useful at some point into
> > there.
> > 
> > This is not what we want.  Most things I see in debugfs support was
> > probably useful for debugging one particular bug but then it was never
> > really useful again in the future.  Those kinds of things can be done
> > locally in someone's tree.
> > 
> > I often see various kinds of "statistics" ending up in these things,
> > or register dumps, both of which are 'ethtool' or similar material.
> Very late to this discussion, but I need to port some of the internal code
> to display the content of a ALE (Address Learning Engine) table maintained
> in hardwareat L2 layer. Currently I have a sysfs implementation that dumps
> information like below.
> 
> root@...-evm:~# cat /sys/devices/platform/soc/2620110.netcp/ale_table
> index 0, raw: 000007fc d000ffff ffffffff, type: addr(1), addr: ff:ff:ff:ff:ff:ff, mcstate: f(3), port mask: 1ff, no super
> index 1, raw: 00000000 10000800 28329a1c, type: addr(1), addr: 08:00:28:32:9a:1c, uctype: persistent(0), port: 0
> index 2, raw: 000007fc d0000100 5e000001, type: addr(1), addr: 01:00:5e:00:00:01, mcstate: f(3), port mask: 1ff, no super
> index 19, raw: 00000004 d000d4be d93db6c1, type: addr(1), addr: d4:be:d9:3d:b6:c1, uctype: touched(3), port: 1
> 
> What is the available interface in kernel to expose this information
> to user space as debugfs is not suggested based on this thread?

This looks a lot like what the mv88e6xxx_port_fdb_dump() callback
returns to DSA when SWITCHDEV_OBJ_ID_PORT_FDB is passed to
switchdev_port_obj_dump() in the switchdev ops.

	  Andrew