linux-kernel - Re: WMI and Kernel:User interface

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Date:   Tue, 13 Jun 2017 09:24:14 -0700
From:   Darren Hart <dvhart@...radead.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Pali Rohár <pali.rohar@...il.com>,
        Christoph Hellwig <hch@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mario Limonciello <mario_limonciello@...l.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Andy Lutomirski <luto@...capital.net>,
        LKML <linux-kernel@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org
Subject: Re: WMI and Kernel:User interface

On Tue, Jun 13, 2017 at 06:05:47PM +0200, Greg Kroah-Hartman wrote:
> On Tue, Jun 13, 2017 at 08:44:19AM -0700, Darren Hart wrote:
> > > In some cases filter function can be simple in some cases hard. I can
> > > image that usage of while listing, plus in some cases also filtering
> > > (when it would be relatively easy to implement).
> > 
> > See my response to Christoph - to address the concern of breaking userspace
> > later, if we consider this a proxy instead of a filter, we can make it
> > transparent to userspace and maintain kernel driver state. The driver can
> > register a wmi_method_proxy callback which can choose to proxy the method call
> > or not. If it does, it can update it's own state and perform the requested
> > action through it's own infrastructure, populate the out buffer and send it back
> > up to userspace. I would hope to see as few of these as possible, but they would
> > allow for protecting the kernel drivers while still enabling userspace usage of
> > WMI.
> 
> Ok, I think we need to see some real code here to get any further with
> this.  There's a reason we don't do big design discussions without
> patches, as that usually answers all of the questions involved.
> 
> Please, let's see some code before anything else.

Agreed. That was my intent earlier with getting the chardev and calling
conventions established.

-- 
Darren Hart
VMware Open Source Technology Center