Date: Mon, 14 Jun 2004 16:10:54 -0700
From: "Randy.Dunlap" <rddunlap@osdl.org>
To: Tim Hockin <thockin@hockin.org>
Cc: cfriesen@nortelnetworks.com, bernd@firmix.at, oliver@neukum.org,
       smfltc@us.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: upcalls from kernel code to user space daemons
Message-Id: <20040614161054.1751506e.rddunlap@osdl.org>
In-Reply-To: <20040614225438.GA22161@hockin.org>
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	<40CE2538.4060603@nortelnetworks.com>
	<20040614225438.GA22161@hockin.org>
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On Mon, 14 Jun 2004 15:54:38 -0700 Tim Hockin wrote:

| On Mon, Jun 14, 2004 at 06:22:48PM -0400, Chris Friesen wrote:
| > > > Not quite.  The userspace is passing data down as well.  I don't know 
| > >how you'd
| > > > do that with read().
| > >
| > >For this you use write().
| 
| > Although I have to admit it's not pretty, and the performance improvements 
| > may not be worth the obfuscation of the code.
| 
| You know, I've never understood why people hate ioctl.  Sometimes, it
| really is what you want.  Why impose structured data onto a 2-way
| unstructred system (read/write) when you have a structured system at hand
| (ioctl).
| 
| I like ioctl() when it makes sense.  read() and write() are for data.
| ioctl is for (tada!) control.
                ^^^^
Looks like data in nuxi format.

Anyway, I agree with you.

--
~Randy
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