Re: RFC: top level compatibles for virtual platforms

[Scott Wood <scottwood@freescale.com>]

On Mon, 11 Jul 2011 15:41:35 -0500
Yoder Stuart-B08248 <B08248@freescale.com> wrote:

> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Monday, July 11, 2011 1:05 PM
> > 
> > Just because Linux does it that way now doesn't mean it needs to.  The interrupt controller
> > has a compatible property.  Match on it like any other device.  You can find which one is the
> > root interrupt controller by looking for nodes with the interrupt-controller property that
> > doesn't have an explicit interrupt-parent (or an interrupts property?  seems to be a conflict
> > between ePAPR and the original interrupt mapping document).
> 
> This may be the right long term thing to do, but restructuring
> how Linux powerpc platforms work is a bigger effort.  I was looking
> for an incremental improvement over what we do now, which is pass
> a compatible of MPC8544DS and P4080DS for these virtual platforms.

A hack is usually easier than doing it right. :-)

Though often the effort required for the latter is overstated, and the
"right long term thing" never makes the jump to "short term plan".

There are a few things that need to be driven off the device tree that
currently aren't -- using some mechanism other than the standard
device model, if necessary (or as a first step) -- and then we need a
does-nothing default platform as the match of last resort.

> However, they _are_ compatible with MPC8544DS and P4080DS so maybe
> leaving the compatible string alone is ok for now.

The virtual platforms are not compatible with MPC8544DS or P4080DS.  Only a
subset of what is on those boards is provided.  And in the case of direct
device assignment, often the things that are present are incompatible (e.g.
different type of eTSEC).

-Scott