From: Neil Brown <neilb@suse.de>
To: "Christopher Friesen" <cfriesen@nortel.com>
Date: Thu, 20 Oct 2005 09:50:57 +1000
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Message-ID: <17238.56289.98600.555278@cse.unsw.edu.au>
Cc: Kyle Moffett <mrmacman_g4@mac.com>, Rick Niles <fniles@mitre.org>,
       linux-kernel@vger.kernel.org
Subject: Re: 26 ways to set a device driver variable from userland
In-Reply-To: message from Christopher Friesen on Wednesday October 19
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On Wednesday October 19, cfriesen@nortel.com wrote:
> Kyle Moffett wrote:
> 
> >> (4) sysfs
> 
> > This is ideal for almost all device driver purposes.
> 
> The one thing that I have yet to see a good solution for is 
> transaction-based operations, where userspace passes in something (could 
> be a command, a new value, a query, etc.) and expects some data in return.
> 

knfsd does this sort of stuff with it's own tiny filesystem.

If you look in fs/libfs.c you will see a section headed
  Transaction based IO
which is exactly for this sort of thing.

Currently I think you need to create your own tiny filesystem (which
isn't much effort if you use the stuff in libfs).

I think I'd like this sort of file to be a standard option for sysfs
attributes, but I haven't looked seriously into the possibility yet.

NeilBrown
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