purpose of /chosen node (was RE: [PATCH] powerpc: delete boot-cpu and chosen nodes from all DTSfiles)

[Yoder Stuart-B08248]

> -----Original Message-----
> From: Kumar Gala [mailto:galak at kernel.crashing.org] 
> Sent: Thursday, February 15, 2007 3:39 PM
> To: Yoder Stuart-B08248
> Cc: Segher Boessenkool; Benjamin Herrenschmidt; 
> linuxppc-dev at ozlabs.org
> Subject: Re: purpose of /chosen node (was RE: [PATCH] 
> powerpc: delete boot-cpu and chosen nodes from all DTSfiles)
> 
> 
> On Feb 15, 2007, at 3:26 PM, Yoder Stuart-B08248 wrote:
> >> -----Original Message-----
> >> From: linuxppc-dev-bounces+b08248=freescale.com at ozlabs.org
> >> [mailto:linuxppc-dev-bounces+b08248=freescale.com at ozlabs.org]
> >> On Behalf Of Segher Boessenkool
> >> Sent: Wednesday, February 14, 2007 7:40 PM
> >> To: David Gibson
> >> Cc: linuxppc-dev at ozlabs.org; Tabi Timur-B04825
> >> Subject: Re: [PATCH] powerpc: delete boot-cpu and chosen
> >> nodes from all DTSfiles
> >>
> >>> My point is that the interrupt-controller property in
> >> /chosen *should*
> >>> be there, but it doesn't make a lot of sense for it to be 
> set by the
> >>> bootloader (because it's a fixed property of the board).
> >>
> >> And that means it shouldn't be in /chosen at all.  It's not
> >> just a fixed property of the board, it is a physical property
> >> of the board.  It doesn't belong in /chosen.
> >
> > I agree with Segher here.  The interrupt-controller property doesn't
> > belong in /chosen.
> >
> > The 1275 OF spec says about /chosen:
> >
> >    Has properties describing parameters chosen or specified at
> >    runtime.
> 
> I want to reiterate something Paul mentioned, any similarity 
> that the  
> device tree has to 1275 is strictly coincidental.

I understand that point, but mixing the types of properties in
/chosen doesn't buy us anything.  We shouldn't be shackled by
the 1275 spec, but having nodes like /chosen with designated
purpose architecturally make sense.

/chosen shouldn't be a catch-all or a convenient place to stick
stuff.  I think in this case following 1275 is a good thing.

Stuart