On Wed, Feb 17, 2016 at 03:18:26PM -0600, Steven Royer wrote:

On 2016-02-16 16:18, Greg Kroah-Hartman wrote:

quoted

On Tue, Feb 16, 2016 at 02:43:13PM -0600, Steven Royer wrote:

quoted

From: Steven Royer <redacted>

The ibmvmc driver is a device driver for the POWER Virtual Management
Channel virtual adapter on the PowerVM platform.  It is used to
communicate with the hypervisor for virtualization management.  It
provides both request/response and asynchronous message support through
the /dev/ibmvmc node.

What is the protocol for that device node?

The protocol is not currently published.  I am pushing on getting it
published, but that process will take time.  If you have a PowerVM system
with NovaLink, it would not be hard to reverse engineer it...  If you don't
have a PowerVM system, then this driver isn't interesting anyway...

You can't just expect us to review this code without at least having a
clue as to how it is supposed to work?

quoted

Where is the documentation here?  Why does this have to be a character
device?  Why can't it fit in with other drivers of this type?

This is a character device for historical reasons.  The short version is
that this driver is a clean-room rewrite of an AIX driver which made it a
character device.  The user space application was ported from AIX to Linux
and it is convenient to have the AIX and Linux drivers match behavior where
possible.

Note that we don't let random userspace applications dictate kernel api
decisions, please make the best choice for this interface without being
influenced by AIX.

quoted

quoted

+/*
+ * IBM Power Systems Virtual Management Channel Support.
+ *
+ * Copyright (c) 2004, 2016 IBM Corp.
+ *   Dave Engebretsen engebret@us.ibm.com
+ *   Steven Royer seroyer@linux.vnet.ibm.com
+ *   Adam Reznechek adreznec@linux.vnet.ibm.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.

I have to ask, but do you really mean "or any later version"?

This actually matches closely to other similar PowerVM virtual device
drivers, like ibmvscsi or ibmveth.

That did not answer the question, picking a license in a cargo-cult
manner is not a wise decision :(