[PATCH v4 0/2] of: populate of_root_node if not set (alternate)

[Frank Rowand <frowand.list@gmail.com>]

This series is a different implementation to achieve the goals of
https://lore.kernel.org/r/20220623105044.152832-1-clement.leger@bootlin.com

In order to apply overlays or create new nodes under the root node, the
kernel expects of_root to be set. On some system where a device-tree was
not provided by firmware (x86 for instance) if CONFIG_OF is enabled,
then we will end up with a null of_root. This series adds support to
create this root node using a builtin dtb and removes the manual
creation of the root node done in unittests.c.

Changes since version 3: (all)
  - also tested on UML (previously only tested on arm)

Changes since version 3: (patch 1/2)
  - refresh for 6.3-rc1
  - unflatten_device_tree() - calculate of_fdt_crc32 if setting
    initial_boot_params to __dtb_empty_root_begin so CRC check
    in of_fdt_raw_init() will not fail

Changes since version 3: (patch 2/2)
  - refresh for 6.3-rc1
  - remove the CONFIG_UML case of populating the devicetree
  - unittest_data_add() - move an EXPECT_BEGIN() to after an error
    check that can result in an early return

Changes since version 2: (patch 1/2)
  - change of __dtb_empty_root_* from "void *" to "uint8_t []"

Changes since version 1: (patch 1/2)
  - refresh for 6.2-rc1
  - update Signed-off-by
  - fix typo in of_fdt.h: s/of_setup/setup_of
  - unflatten_device_tree(): validate size in header field dtb_empty_root
    that will be used to copy dtb_empty_root
  - add Kconfig option to manually select CONFIG_OF_EARLY_FLATTREE

Changes since version 1: (patch 2/2)
  - refresh for 6.2-rc1
  - update Signed-off-by
  - fix formatting error (leading space) in patch comment



Frank Rowand (2):
  of: create of_root if no dtb provided
  of: unittest: treat missing of_root as error instead of fixing up

 drivers/of/Kconfig        |  7 ++++++-
 drivers/of/Makefile       |  2 +-
 drivers/of/empty_root.dts |  6 ++++++
 drivers/of/fdt.c          | 29 ++++++++++++++++++++++++++++-
 drivers/of/unittest.c     | 16 ++++------------
 include/linux/of_fdt.h    |  2 ++
 init/main.c               |  2 ++
 7 files changed, 49 insertions(+), 15 deletions(-)
 create mode 100644 drivers/of/empty_root.dts

-- 
Frank Rowand <frowand.list@gmail.com>