[PATCH 1/2] kbuild: Pass -Eno-node_name_not_empty to DTC if supported

[PATCH 1/2] kbuild: Pass -Eno-node_name_not_empty to DTC if supported

[Marek Vasut]

Since DTC 7c78c8542d73 ("Added empty node name check") , U-Boot binman
use of placeholder node names such as @fdt-SEQ and @config-SEQ triggers
DTC ERROR (node_name_not_empty). Inhibit the error, as these placeholder
nodes are updated by binman and replaced by proper nodes, the encoding
in DTB is temporary. Since -Eno-node_name_not_empty is only available in
DTC 1.8.0 and newer, introduce "dtc-option" make function which is very
similar to "cc-option" and other such Kbuild functions, and add the DTC
option conditionally.

This can be triggered on e.g. Debian Testing (as of 2026-09-07) when
using system DTC to build a DT which include binman placeholder nodes:

$ export DTC=/usr/bin/dtc
$ $DTC --version
Version: DTC 1.8.1
$ r8a779g3_sparrowhawk_defconfig
$ make -j$(nproc)
...
./arch/arm/dts/r8a779g0-u-boot.dtsi:61.16-70.9: ERROR (node_name_not_empty): /binman/section/u-boot/fit/images/@fdt-SEQ: Empty node name
./arch/arm/dts/r8a779g0-u-boot.dtsi:76.19-80.9: ERROR (node_name_not_empty): /binman/section/u-boot/fit/configurations/@config-SEQ: Empty node name
ERROR: Input tree has errors, aborting (use -f to force output)
Check /path/to/dts/upstream/src/arm64/renesas/.r8a779g3-sparrow-hawk.dtb.pre.tmp for errors

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Héctor Orón Martínez <zumbi@debian.org>
Cc: Mattia Maldini <mattia512maldini@gmail.com>
Cc: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Vagrant Cascadian <vagrant@debian.org>
Cc: u-boot@lists.u-boot-project.org
---
 scripts/Makefile.lib | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 122c8e78204..330ab3892e9 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -378,6 +378,19 @@ DTC_FLAGS += $(DTC_FLAGS_$(basetarget))
 # Set -@ if the target is a base DTB that overlay is applied onto
 DTC_FLAGS += $(if $(filter $(patsubst $(obj)/%,%,$@), $(base-dtb-y)), -@)
 
+# dtc-option
+# Usage: DTC_FLAGS += $(call dtc-option,-Eno-node_name_not_empty)
+dtc-option = $(call try-run,\
+	printf '/dts-v1/; / {};' | $(DTC) $(1) -I dts -O dtb -o /dev/null,$(1),$(2))
+
+# Since DTC 7c78c8542d73 ("Added empty node name check") , U-Boot binman
+# use of placeholder node names such as @fdt-SEQ and @config-SEQ triggers
+# DTC ERROR (node_name_not_empty). Inhibit the error, as these placeholder
+# nodes are updated by binman and replaced by proper nodes, the encoding
+# in DTB is temporary. Since -Eno-node_name_not_empty is only available in
+# DTC 1.8.0 and newer, add the option conditionally.
+DTC_FLAGS += $(call dtc-option, -Eno-node_name_not_empty)
+
 # Generate an assembly file to wrap the output of the device tree compiler
 quiet_cmd_dt_S_dtb= DTBS    $@
 # Modified for U-Boot
-- 
2.53.0

[PATCH 2/2] kbuild: Do not pass -Wno-graph_child_address to DTC unless supported

[Marek Vasut]

DTC commit cba90ce82064 ("checks: Remove check for graph child addresses")
removed -Wno-graph_child_address command line parameter. Apply this option
only to DTC older than 1.8.0.

This can be triggered on e.g. Debian Testing (as of 2026-09-07) when
using system DTC:

$ export DTC=/usr/bin/dtc
$ $DTC --version
Version: DTC 1.8.1
$ r8a779g3_sparrowhawk_defconfig
$ make -j$(nproc)
...
FATAL ERROR: Unrecognized check name "graph_child_address"
Check /path/to/dts/upstream/src/arm64/renesas/.r8a779g3-sparrow-hawk.dtb.pre.tmp for errors

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Héctor Orón Martínez <zumbi@debian.org>
Cc: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Cc: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Vagrant Cascadian <vagrant@debian.org>
Cc: u-boot@lists.u-boot-project.org
---
 scripts/Makefile.lib | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 330ab3892e9..3817115816b 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -357,7 +357,6 @@ DTC_FLAGS += -Wno-unit_address_vs_reg \
 	-Wno-unit_address_format \
 	-Wno-avoid_unnecessary_addr_size \
 	-Wno-alias_paths \
-	-Wno-graph_child_address \
 	-Wno-simple_bus_reg \
 	-Wno-unique_unit_address \
 	-Wno-pci_device_reg
@@ -391,6 +390,11 @@ dtc-option = $(call try-run,\
 # DTC 1.8.0 and newer, add the option conditionally.
 DTC_FLAGS += $(call dtc-option, -Eno-node_name_not_empty)
 
+# Since cba90ce82064 ("checks: Remove check for graph child addresses")
+# the -Wno-graph_child_address is no longer available. Apply the option
+# only to DTC older than 1.8.0.
+DTC_FLAGS += $(call dtc-option, -Wno-graph_child_address)
+
 # Generate an assembly file to wrap the output of the device tree compiler
 quiet_cmd_dt_S_dtb= DTBS    $@
 # Modified for U-Boot
-- 
2.53.0

Re: [PATCH 1/2] kbuild: Pass -Eno-node_name_not_empty to DTC if supported

[Rasmus Villemoes]

On Sun, Oct 04 2026, Marek Vasut <marek.vasut+renesas@mailbox.org> wrote:

> Since DTC 7c78c8542d73 ("Added empty node name check") , U-Boot binman
> use of placeholder node names such as @fdt-SEQ and @config-SEQ triggers
> DTC ERROR (node_name_not_empty). Inhibit the error, as these placeholder
> nodes are updated by binman and replaced by proper nodes, the encoding
> in DTB is temporary. Since -Eno-node_name_not_empty is only available in
> DTC 1.8.0 and newer, introduce "dtc-option" make function which is very
> similar to "cc-option" and other such Kbuild functions, and add the DTC
> option conditionally.

Is this the best way to handle this? This also removes the error for
empty node names that might appear in the "real" part of the dtb, no?

I'm not really familiar with the binman magic, but is there any reason
those placeholder nodes cannot be binman@fdt-SEQ and binman@config-SEQ,
or anything like that? Sure, the binman code would need updating and
there would be some -u-boot.dtsi files to update, but I'm currently
counting less than 70 instances, about half in tests, so it would not be
a lot of churn, and changing it now would mean we avoid having to carry
around that dtc flag forever.

Rasmus

Re: [PATCH 2/2] kbuild: Do not pass -Wno-graph_child_address to DTC unless supported

[Tom Rini]

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On Sun, Oct 04, 2026 at 08:17:43AM +0200, Marek Vasut wrote:

> DTC commit cba90ce82064 ("checks: Remove check for graph child addresses")
> removed -Wno-graph_child_address command line parameter. Apply this option
> only to DTC older than 1.8.0.
> 
> This can be triggered on e.g. Debian Testing (as of 2026-09-07) when
> using system DTC:
> 
> $ export DTC=/usr/bin/dtc
> $ $DTC --version
> Version: DTC 1.8.1
> $ r8a779g3_sparrowhawk_defconfig
> $ make -j$(nproc)
> ...
> FATAL ERROR: Unrecognized check name "graph_child_address"
> Check /path/to/dts/upstream/src/arm64/renesas/.r8a779g3-sparrow-hawk.dtb.pre.tmp for errors
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
> ---

We should just drop it unconditionally, both to easier match up with
future kernel re-syncs and also because the DTC commit (as I read it)
says the check itself was flawed / not useful.

-- 
Tom

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