Re: [PATCH 1/2] OLPC: Add support for calling into Open Firmware

[Andres Salomon]

On Mon, 21 Apr 2008 20:18:11 +0100
David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:

> On Mon, 2008-04-21 at 13:03 -0400, Andres Salomon wrote:
> > Quite simply, it's a lot more work (*and* we have to play nice w/
> > sparc and ppc).  
> 
> It's only more work because we did it the wrong way in the first place.
> If only someone had pointed it out at the time... :)
> 

Yes, and if only we had an infinite number of kernel hackers who had time
to work on such things, then we could've done things differently.


> For interaction with device-tree properties in generic code, you should
> be using the functions defined in <linux/of.h>.
> 

At the time [the OFW interface] was written, linux/of.h didn't *exist*.


> Creating the static device-tree before we quiesce OpenFirmware surely
> shouldn't be so hard? Can't we cut and paste most of that code anyway?
> 

We're not adding a device tree right now, we're adding a method for
querying OFW for information.  Eventually that information should be
obtained from a device tree.  However, that's going to take additional time,
and I'd like to get rid of some of these patches that we've been carrying
around.


> > I had intended to eventually do it, but first I wanted
> > to get this stuff in for 2.6.26 so that we could at least boot upstream
> > kernels on XOs.
> 
> Is it only the things in your second patch which need to be made to
> work? One of them was already working, by grubbing around in the BIOS
> directly -- so all we need is the board revision, isn't it? Can we get
> that from the EC for now?
> 


Well, no, it wasn't already working; that's the reason this whole
thread started.  It was crashing someone's machine.  That's why the OFW
interface, as imperfect as it is, is an _improvement_.



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