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    SubjectRe: [PATCH 1/3] of: always populate a root node
    On Wed, Apr 27, 2022 at 11:45:00AM +0200, Clément Léger wrote:
    > When enabling CONFIG_OF on a platform where of_root is not populated by
    > firmware, we end up without a root node. In order to apply overlays and
    > create subnodes of the root node, we need one. This commit creates an
    > empty root node if not present.

    The existing unittest essentially does the same thing for running the
    tests on non-DT systems. It should be modified to use this support
    instead. Maybe that's just removing the unittest code that set of_root.

    I expect Frank will have some comments.

    > Co-developed-by: Rob Herring <robh@kernel.org>
    > Signed-off-by: Rob Herring <robh@kernel.org>
    > Signed-off-by: Clément Léger <clement.leger@bootlin.com>
    > ---
    > drivers/of/base.c | 16 ++++++++++++++--
    > 1 file changed, 14 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/of/base.c b/drivers/of/base.c
    > index e7d92b67cb8a..6b8584c39f73 100644
    > --- a/drivers/of/base.c
    > +++ b/drivers/of/base.c
    > @@ -177,6 +177,19 @@ void __init of_core_init(void)
    > pr_err("failed to register existing nodes\n");
    > return;
    > }
    > +
    > + if (!of_root) {
    > + of_root = kzalloc(sizeof(*of_root), GFP_KERNEL);
    > + if (!of_root) {
    > + mutex_unlock(&of_mutex);
    > + pr_err("failed to create root node\n");
    > + return;
    > + }
    > +
    > + of_root->full_name = "/";
    > + of_node_init(of_root);
    > + }
    > +
    > for_each_of_allnodes(np) {
    > __of_attach_node_sysfs(np);
    > if (np->phandle && !phandle_cache[of_phandle_cache_hash(np->phandle)])
    > @@ -185,8 +198,7 @@ void __init of_core_init(void)
    > mutex_unlock(&of_mutex);
    >
    > /* Symlink in /proc as required by userspace ABI */
    > - if (of_root)
    > - proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
    > + proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
    > }
    >
    > static struct property *__of_find_property(const struct device_node *np,
    > --
    > 2.34.1
    >
    >

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