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Date:   Mon, 30 Jul 2018 16:37:14 +0200
From:   Michal Kubecek <mkubecek@suse.cz>
To:     Jiri Pirko <jiri@resnulli.us>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        David Miller <davem@davemloft.net>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Roopa Prabhu <roopa@cumulusnetworks.com>,
        Jakub Kicinski <kubakici@wp.pl>,
        "John W. Linville" <linville@tuxdriver.com>
Subject: Re: [RFC PATCH net-next v2 09/17] ethtool: implement GET_DRVINFO
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Message-ID: <20180730143714.tlvze2xas2kk7zqo@unicorn.suse.cz>
References: <cover.1532953989.git.mkubecek@suse.cz>
 <4dcd60f25efe368ada4e0c035dc1d7612ab59132.1532953989.git.mkubecek@suse.cz>
 <20180730132107.GB10626@nanopsycho>
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On Mon, Jul 30, 2018 at 03:21:07PM +0200, Jiri Pirko wrote:
> Mon, Jul 30, 2018 at 02:53:27PM CEST, mkubecek@suse.cz wrote:
> 
> [...]
> 
> >+/* GET_DRVINFO / SET_DRVINFO */
> >+
> >+enum {
> >+	ETHA_DRVINFO_UNSPEC,
> >+	ETHA_DRVINFO_DEV,			/* nest - ETHA_DEV_* */
> >+	ETHA_DRVINFO_DRIVER,			/* string */
> >+	ETHA_DRVINFO_VERSION,			/* string */
> >+	ETHA_DRVINFO_FWVERSION,			/* string */
> >+	ETHA_DRVINFO_BUSINFO,			/* string */
> >+	ETHA_DRVINFO_EROM_VER,			/* string */
> >+	ETHA_DRVINFO_N_PRIV_FLAGS,		/* u32 */
> >+	ETHA_DRVINFO_N_STATS,			/* u32 */
> >+	ETHA_DRVINFO_TESTINFO_LEN,		/* u32 */
> >+	ETHA_DRVINFO_EEDUMP_LEN,		/* u32 */
> >+	ETHA_DRVINFO_REGDUMP_LEN,		/* u32 */
> 
> This is a nice example of why 1:1 ioctl->netlink conversion would be
> a big mistake.
> 
> I understand that for ioclt, getting lengths of various things is
> important. Userspace can prepare buffer for next ioctl which would
> actually do dump transfer. However in netlink, this is totally pointless
> as the dump goes into userspace in multiple netlink messages.

Right, I already mentioned this in the ToDo part of cover letter. It
makes indeed little sense to put this information here - and even less
to put only dome of the counts and lengths.

Michal Kubecek