[XenPPC] Re: [RFC] consolidated libdt proposal

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

On Tue, 2006-08-08 at 11:04 -0700, Mark A. Greer wrote:
> 
> Except for not being able to extend a property (see below),
> I think it does meet my needs (at least as I know them today).

Great.

> However, I was hoping to keep the interfaces in the bootwrapper
> similar to the ones used in the kernel.  To that end, I had a
> routine to find a device node and other routines to find and modify
> a property within that node.  I didn't notice a "finddevice" type of
> function to find a device node.  Would you have a problem adding one?

The way property modification works now is this:
        p = ft_get_prop(tree, "/xen/console/interrupts", &len);
        if ((NULL == p) || (len != foolen))
                return;
        *p = cpu_to_be32(foo);
(That does need to be hidden in a yet-to-be-written ft_set_prop().)

If necessary, it looks like it would be possible to modify ft_get_prop()
to return a pointer to the beginning of the node structure, but is it
really necessary? Do you have code that would be difficult to convert to
using
        ft_set_prop(tree, "/node/prop", buf, buflen);
?

> > One limitation of the attached code is that it doesn't support changing
> > the *size* of properties, though I don't think that would be too
> > difficult to add if needed.
> 
> If we're going to allow cmdline editing in the bootwrapper, we would
> need to extend the size of a property.  We've never really talked about
> cmdline editing in the powerpc branch but I assume that its a good
> thing(tm).  I know I would like to have it so, IMHO, I think we should
> add it (and therefore require extending a property).

I agree, and it shouldn't be too much work. I'll take a look later this
week, if nobody else has.

-- 
Hollis Blanchard
IBM Linux Technology Center


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