[PATCH v3 7/7] of_overlay: Add option to apply overlay to live tree

[Sascha Hauer]

On Tue, Mar 14, 2023 at 03:59:29PM +0100, Michael Riesch wrote:
> Hi Sascha,
> 
> On 3/10/23 10:42, Sascha Hauer wrote:
> > The of_overlay command currently only supports applying overlays to the
> > Linux device tree. Add an option to apply an overlay to the live tree.
> > Using this option will apply the overlay and also triggers rescanning
> > the device tree in case new devices have been added.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> > ---
> >  commands/of_overlay.c | 38 ++++++++++++++++++++++++++++++++++----
> >  1 file changed, 34 insertions(+), 4 deletions(-)
> > 
> > diff --git a/commands/of_overlay.c b/commands/of_overlay.c
> > index b3660b4bf1..1d68e31ef2 100644
> > --- a/commands/of_overlay.c
> > +++ b/commands/of_overlay.c
> > @@ -17,10 +17,20 @@ static int do_of_overlay(int argc, char *argv[])
> >  	struct fdt_header *fdt;
> >  	struct device_node *overlay;
> >  	size_t size;
> > +	bool live_tree = false;
> > +	int opt;
> >  
> > -	if (argc != 2)
> > +	if (argc < 2)
> >  		return COMMAND_ERROR_USAGE;
> >  
> > +	while ((opt = getopt(argc, argv, "l")) > 0) {
> > +		switch (opt) {
> > +		case 'l':
> > +			live_tree = true;
> > +			break;
> > +		}
> > +	}
> > +
> >  	fdt = read_file(argv[optind], &size);
> 
> of course this is not the intended usage, but "of_overlay -l" (i.e.,
> skipping the overlay argument) throws an exception.

Okay, will fix.

> 
> >  	if (!fdt) {
> >  		printf("cannot read %s\n", argv[optind]);
> > @@ -32,7 +42,14 @@ static int do_of_overlay(int argc, char *argv[])
> >  	if (IS_ERR(overlay))
> >  		return PTR_ERR(overlay);
> >  
> > -	ret = of_register_overlay(overlay);
> > +	if (live_tree) {
> > +		ret = of_overlay_apply_tree(of_get_root_node(), overlay);
> 
> If I pass a meaningful argument ("of_overlay -l path_to_my_overlay"), I get
> 
> ERROR: of_resolver: __symbols__ missing from base devicetree
> cannot apply oftree overlay: Invalid argument
> of_overlay: Invalid argument
> 
> in return. The base device tree does not contain any __symbols__
> sections indeed. How can I activate the generation of this section?

Please enable CONFIG_OF_OVERLAY_LIVE. Maybe we can improve this a bit to
make this clearer somehow / somewhere,

Sascha

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