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Subject: Re: [PATCH v2 01/11] of: Load KUnit DTB from of_core_init()
From:   Stephen Boyd <sboyd@kernel.org>
Cc:     Michael Turquette <mturquette@baylibre.com>,
        linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
        patches@lists.linux.dev,
        Brendan Higgins <brendan.higgins@linux.dev>,
        David Gow <davidgow@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        rafael@kernel.org, Frank Rowand <frowand.list@gmail.com>,
        Christian Marangi <ansuelsmth@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        devicetree@vger.kernel.org, linux-kselftest@vger.kernel.org,
        kunit-dev@googlegroups.com, Maxime Ripard <maxime@cerno.tech>
To:     Rob Herring <robh@kernel.org>
Date:   Tue, 21 Mar 2023 11:24:45 -0700
User-Agent: alot/0.10
Precedence: bulk

Quoting Stephen Boyd (2023-03-21 11:15:19)
> Quoting Rob Herring (2023-03-21 10:33:03)
> > On Wed, Mar 15, 2023 at 11:37:18AM -0700, Stephen Boyd wrote:
> > > diff --git a/drivers/of/of_test.c b/drivers/of/of_test.c
> > > new file mode 100644
> > > index 000000000000..a4d70ac344ad
> > > --- /dev/null
> > > +++ b/drivers/of/of_test.c
> > > @@ -0,0 +1,43 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * KUnit tests for OF APIs
> > > + */
> > > +#include <linux/kconfig.h>
> > > +#include <linux/of.h>
> > > +
> > > +#include <kunit/test.h>
> > > +
> > > +/*
> > > + * Test that the root node / exists.
> > > + */
> > > +static void dtb_root_node_exists(struct kunit *test)
> > > +{
> > > +     KUNIT_EXPECT_NOT_ERR_OR_NULL(test, of_find_node_by_path("/"));
> > > +}
> > > +
> > > +/*
> > > + * Test that the /__symbols__ node exists.
> > > + */
> > > +static void dtb_symbols_node_exists(struct kunit *test)
> > > +{
> > > +     KUNIT_EXPECT_NOT_ERR_OR_NULL(test, of_find_node_by_path("/__sym=
bols__"));
> > > +}
> >=20
> > Many base DTs will not have this. And the kunit tests themselves=20
> > shouldn't need it because they should be independent of the base tree.
> >=20
>=20
> When I try to apply an overlay it fails=20
>=20
>  OF: overlay: no fragments or symbols in overlay
>  OF: overlay: init_overlay_changeset() failed, ret =3D -22
>      # of_overlay_apply_kunit_apply: ASSERTION FAILED at drivers/of/overl=
ay_test.c:18
>      Expected 0 =3D=3D ({ extern uint8_t __dtbo_kunit_overlay_test_begin[=
]; extern uint8_t __dtbo_kunit_overlay_test_end[]; __of_overlay_apply_kunit=
((test), __dtbo_kunit_overlay_test_begin, __dtbo_kunit_overlay_test_end); }=
), but
>          ({ extern uint8_t __dtbo_kunit_overlay_test_begin[]; extern uint=
8_t __dtbo_kunit_overlay_test_end[]; __of_overlay_apply_kunit((test), __dtb=
o_kunit_overlay_test_begin, __dtbo_kunit_overlay_test_end); }) =3D=3D -12 (=
0xfffffffffffffff4)
>  [FAILED] of_overlay_apply_kunit_apply
>=20
> Now I'm trying to hack on the fake root node to see if I can make it work.
>=20

Aha I figured it out. Needed to read more documentation.

---8<---
diff --git a/drivers/of/kunit_overlay_test.dtso b/drivers/of/kunit_overlay_=
test.dtso
index e3ced1467dd9..7688f9ef1b6b 100644
--- a/drivers/of/kunit_overlay_test.dtso
+++ b/drivers/of/kunit_overlay_test.dtso
@@ -2,7 +2,7 @@
 /dts-v1/;
 /plugin/;
=20
-/ {
+&{/} {
 	test-kunit {
 		compatible =3D "test,kunit-empty";
 	};