Re: Request review of device tree documentation

From: Mike Rapoport <mike@compulab•co.il>
To: Mitch Bradley <wmb@firmworks•com>
Cc: Nicolas Pitre <nico@fluxnic•net>,
	microblaze-uclinux@itee•uq.edu.au,
	devicetree-discuss <devicetree-discuss@lists•ozlabs.org>,
	Jamie Lokier <jamie@shareable•org>,
	linuxppc-dev <linuxppc-dev@ozlabs•org>,
	Mike Rapoport <mike@compulab•co.il>,
	Dan Malek <ppc6dev@digitaldans•com>,
	Jeremy Kerr <jeremy.kerr@canonical•com>,
	linux-arm-kernel@lists•infradead.org,
	David Gibson <david@gibson•dropbear.id.au>
Subject: Re: Request review of device tree documentation
Date: Wed, 16 Jun 2010 09:09:44 +0300	[thread overview]
Message-ID: <4C186AA8.4040709@compulab.co.il> (raw)
In-Reply-To: <4C165FD1.6080505@firmworks.com>

Mitch Bradley wrote:

> The second topic is the hypothetical use of OFW as a HAL. That will not 
> happen for several reasons.  The opposition to the idea is widespread 
> and deeply held, and there are good arguments to support that 
> opposition.   Furthermore, the economic conditions necessary for the 
> creation of such a HAL do not exist in the ARM world, nor indeed in the 
> Linux world in general.  (The necessary condition is the ability for one 
> company to impose a substantial change by fiat - essentially a monopoly 
> position.)
> 
> Shall we agree, then, that any further discussion of the HAL issue is 
> "just for fun", and that nobody needs to feel threatened that it would 
> actually happen?

I've recently worked with vendor versions of U-Boot for advanced ARM 
SoCs. There is already *huge* chunk of HAL code in those versions. And 
if there would be possibility to have callbacks into the firmware these 
chunks would only grow, IMHO.

> The potential for "vendors breaking out of the debugging use case and 
> turning it into a HAL" is miniscule, because
> 
> a) The callback is disabled by default
> b) The technical challenges of the callback interface limit its 
> applicability to specific "wizard user" scenarios
> c) OFW is unlikely to achieve sufficient market penetration for the HAL 
> thing to be worth doing
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists•infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 
Sincerely yours,
Mike.