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From:   Salil Mehta <salil.mehta@huawei.com>
To:     Andrew Lunn <andrew@lunn.ch>
CC:     "davem@davemloft.net" <davem@davemloft.net>,
        "yuvalm@mellanox.com" <yuvalm@mellanox.com>,
        "leon@kernel.org" <leon@kernel.org>,
        "Zhuangyuzeng (Yisen)" <yisen.zhuang@huawei.com>,
        "lipeng (Y)" <lipeng321@huawei.com>,
        "mehta.salil@opnsrc.net" <mehta.salil@opnsrc.net>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
        Linuxarm <linuxarm@huawei.com>
Subject: RE: [RFC PATCH 00/10] net: hns3: Adds support of debugfs to HNS3
 driver
Thread-Topic: [RFC PATCH 00/10] net: hns3: Adds support of debugfs to HNS3
 driver
Thread-Index: AQHUeHjKl7L/rK4Ga0KUIgRpv+IpHaVH+aMAgAKzxPA=
Date:   Sun, 11 Nov 2018 15:12:34 +0000
Message-ID: <F4CC6FACFEB3C54C9141D49AD221F7F93BF9FC72@FRAEML521-MBS.china.huawei.com>
References: <20181109220743.10264-1-salil.mehta@huawei.com>
 <20181109224346.GD5259@lunn.ch>
In-Reply-To: <20181109224346.GD5259@lunn.ch>
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Hi Andrew,
Thanks for replying. Sorry, for not being prompt as I was
traveling.

Please find some further follow-up questions below

Salil.

> From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma-
> owner@vger.kernel.org] On Behalf Of Andrew Lunn
> Sent: Friday, November 9, 2018 10:44 PM
> To: Salil Mehta <salil.mehta@huawei.com>
> Cc: davem@davemloft.net; yuvalm@mellanox.com; leon@kernel.org;
> Zhuangyuzeng (Yisen) <yisen.zhuang@huawei.com>; lipeng (Y)
> <lipeng321@huawei.com>; mehta.salil@opnsrc.net; netdev@vger.kernel.org;
> linux-kernel@vger.kernel.org; linux-rdma@vger.kernel.org; Linuxarm
> <linuxarm@huawei.com>
> Subject: Re: [RFC PATCH 00/10] net: hns3: Adds support of debugfs to
> HNS3 driver
> 
> > 3. Debugfs looks more unstructured unlike sysfs. Is there any
> >    de-facto standard of the user-api or drivers are allowed to
> >    use it in any way to expose the information from kernel.
> 
> Hi Salil
> 
> You don't really have a user api using debugfs, because debugfs is
> unstable. Anything can change at any time. Any user tools which use
> debugfs can be expected to break at any time as the information in
> debugfs changes. debugfs is for debug, not to export an API. And in
> production systems, it is often not mounted.


Sure, I understand. 

> 
> As much as possible, you are recommended to use existing APIs,
> ethtool, devlink, etc.


Agreed. But what about if we want to expose anything related to
firmware to user-space using the debugfs, assuming we are presenting
information in structured way and not as a black-box to some user-space
application. Is it something which might be discouraged?

Many Thanks