Subject: Re: [PATCH] enclosure: add support for enclosure services
From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: kristen.c.accardi@intel.com
Cc: ltuikov@yahoo.com, linux-scsi <linux-scsi@vger.kernel.org>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       linux-ide <linux-ide@vger.kernel.org>, jeff@garzik.org
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Date: Wed, 13 Feb 2008 12:17:09 -0600
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On Wed, 2008-02-13 at 09:45 -0800, Kristen Carlson Accardi wrote:
> I don't think I'm arguing whether or not your solution may work, what I
> am arguing is really a more philosophical point.  Not "can we do it
> this way", but "should we do it way".  I am of the opinion that
> management belongs in userspace.  I also am of the opinion that if you
> can successfully accomplish something in user space, you should.  I
> also believe that even if you provide this basic interface, all system
> vendors are going to provide libraries on top of that to customize it,
> so you've not added much value to just a simple message passing
> interface.

I'm not necessarily arguing against that.  However, what you're
providing is slightly more than just a userspace tap into the enclosure.
You're adding a file to display and control the enclosure state
(sw_activity).  This constitutes an ad-hoc sysfs interface.  I'm not
telling you not to do it, but I am pleading that if we have to have all
these sysfs interfaces, lets at least do it in a uniform way.

Enclosures are such nasty beasts, that even the job of getting a tap
into them is problematic, so if we have a different tap infrastructure
for every different enclosure type and connection it's still going to be
pretty unmanageable to a userspace interface.

> So, I'm happy to defer to Jeff's judgement call here - I just want to
> do what's right for our customers and get an enclosure management
> interface for SATA exposed, preferrably in time for the 2.6.26 merge
> window.  If he prefers your design, I'll disagree, but commit to his
> decision and try to get this to work for SATA. If he'd rather see
> something along the lines of what I proposed, then since it is 100% self
> contained in the SATA subsystem, it shouldn't impact whatever you
> want to do in the SCSI subsystem.

James


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