* [ptxdist] [RFC PATCH 2/2] kernel: validate device trees against the DT schema
2026-07-30 13:07 [ptxdist] [RFC PATCH 0/2] Run DT schema check on selected device trees Bruno Thomsen
2026-07-30 13:07 ` [ptxdist] [RFC PATCH 1/2] host-system-python: add dtschema Bruno Thomsen
@ 2026-07-30 13:07 ` Bruno Thomsen
1 sibling, 0 replies; 3+ messages in thread
From: Bruno Thomsen @ 2026-07-30 13:07 UTC (permalink / raw)
To: ptxdist; +Cc: Bruno Thomsen
Make it possible to do device tree validation on
dts/dtsi during development and preparation for
upstream.
Signed-off-by: Bruno Thomsen <bruno.thomsen@gmail.com>
---
platforms/kernel.in | 25 +++++++++++++++++++++++++
rules/kernel.make | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 61 insertions(+)
diff --git a/platforms/kernel.in b/platforms/kernel.in
index 2c6d906e8..79a414fd8 100644
--- a/platforms/kernel.in
+++ b/platforms/kernel.in
@@ -11,6 +11,8 @@ menuconfig KERNEL
select HOST_LZ4 if KERNEL_LZ4
select HOST_LIBKMOD if KERNEL_MODULES
select HOST_SYSTEM_BC
+ select HOST_SYSTEM_PYTHON3 if KERNEL_DTB_CHECK
+ select HOST_SYSTEM_PYTHON3_DTSCHEMA if KERNEL_DTB_CHECK
select HOST_OPENSSL if KERNEL_OPENSSL
select HOST_LIBELF if KERNEL_LIBELF
select HOST_BINDGEN_CLI if KERNEL_RUST
@@ -232,6 +234,29 @@ config KERNEL_DTSO
endif
+config KERNEL_DTB_CHECK
+ bool
+ depends on KERNEL_DTB
+ prompt "validate device trees against the DT schema"
+ help
+ Additionally build the device trees with the kernel build system
+ ('make CHECK_DTBS=y <board>.dtb') to validate them against the
+ device tree bindings in Documentation/devicetree/bindings.
+ Problems are reported as warnings, they do not break the build.
+
+ This requires the 'dtschema' python package on the build host and
+ it noticeably increases the build time of the kernel, because the
+ schema of all bindings must be processed first.
+
+ Only device trees that are part of the kernel tree can be checked.
+ Each file in KERNEL_DTS is looked up in KERNEL_DTS_PATH and the
+ first match below a 'boot/dts' directory is checked, even if the
+ device tree itself is built from an earlier entry in the search
+ path. Device trees without such a match are skipped with a
+ warning. So for device trees in a vendor directory, that directory
+ must be part of KERNEL_DTS_PATH, e.g.
+ "${KERNEL_DIR}/arch/${GENERIC_KERNEL_ARCH}/boot/dts/ti/omap".
+
config KERNEL_CODE_SIGNING
prompt "use code signing infrastructure"
select KERNEL_OPENSSL
diff --git a/rules/kernel.make b/rules/kernel.make
index af0dd3913..eaed71023 100644
--- a/rules/kernel.make
+++ b/rules/kernel.make
@@ -215,6 +215,36 @@ KERNEL_MAKE_OPT = \
$(KERNEL_IMAGE) \
$(call ptx/ifdef, PTXCONF_KERNEL_MODULES,modules)
+#
+# device tree validation
+#
+# The kernel build system can only validate device trees from the kernel tree.
+# Look up the device trees in KERNEL_DTS_PATH and use the first match below a
+# 'boot/dts' directory.
+#
+kernel/dtb-check-file = \
+ $(firstword $(foreach dts, \
+ $(call ptx/in-path-all,KERNEL_DTS_PATH,$(1)), \
+ $(if $(findstring /boot/dts/,$(dts)),$(dts))))
+
+# the dtb make targets are relative to arch/<arch>/boot/dts
+kernel/dtb-check-target = \
+ $(patsubst %.dts,%.dtb,$(patsubst /%,%,$(word 2, \
+ $(subst /boot/dts,$(ptx/def/space), \
+ $(call kernel/dtb-check-file,$(1))))))
+
+KERNEL_DTB_CHECK_FILES = $(strip \
+ $(foreach dts,$(KERNEL_DTS),$(call kernel/dtb-check-target,$(dts))))
+
+KERNEL_DTB_CHECK_SKIPPED = $(strip \
+ $(foreach dts,$(KERNEL_DTS), \
+ $(if $(call kernel/dtb-check-file,$(dts)),,$(dts))))
+
+KERNEL_DTB_CHECK_OPT = \
+ $(KERNEL_SHARED_OPT) \
+ CHECK_DTBS=y \
+ $(KERNEL_DTB_CHECK_FILES)
+
KERNEL_TOOL_PERF_OPTS := \
-C $(KERNEL_DIR)/tools/perf \
O=$(KERNEL_BUILD_DIR)/tools/perf \
@@ -263,6 +293,12 @@ $(STATEDIR)/kernel.compile:
$(KERNEL_BUILD_DIR)/usr/initramfs_data.cpio.* \
$(KERNEL_BUILD_DIR)/usr/.initramfs_data.cpio.*
@$(call world/compile, KERNEL)
+ifdef PTXCONF_KERNEL_DTB_CHECK
+ @$(foreach dts, $(KERNEL_DTB_CHECK_SKIPPED), \
+ echo "dtb-check: skipping '$(dts)': no match below 'boot/dts' in KERNEL_DTS_PATH";)
+ @$(if $(KERNEL_DTB_CHECK_FILES), \
+ $(call world/execute, KERNEL, $(MAKE) $(KERNEL_DTB_CHECK_OPT)))
+endif
ifdef PTXCONF_KERNEL_TOOL_PERF
@mkdir -p $(KERNEL_BUILD_DIR)/tools/perf
@$(call compile, KERNEL, $(KERNEL_TOOL_PERF_OPTS))
--
2.55.0
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