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kbuild: Support directory targets for building DTBs

PATCH Superseded Rob Herring (Arm) 3 participants 4 messages Nov 20, 2025 – Nov 21, 2025

Subsystems (6)
Arm (32-bit) Kbuild MIPS RISC-V +2 more subsystems

v2 of 5 Superseded Latest is v5 →

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Rob Herring (Arm)

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#0 lore raw

PATCH v2 1/1 kbuild: Support directory targets for building DTBs

It is useful to be able to build all the DTBs for a vendor. One can list all the .dts files in a directory and convert those to %.dtb targets, but that doesn't work for base+overlay DTB targets.

Adding the dts subdirectory is straight-forward, but building the DTBs should only happen for certain targets (dtbs, dtbs_check, %.dtb, %.dtbo, and the directory target(s)).

The 'scripts_dtc' rule doesn't really depend on 'dt_binding_schemas', but the directory target only depends on 'scripts' which depends on 'scripts_dtc'.

---
Please ack and I'll take this in the DT tree.

I don't really like looking at MAKECMDGOALS, but that's the only way I could come up with that works. Maybe someone knows a better way.

v2:
- Convert arm, mips and riscv. The other DT enabled arches don't have vendor directories.
- Link to v1: https://lore.kernel.org/all/[email protected]/

---
 Makefile              | 2 +-
 arch/arm/Kbuild       | 2 ++
 arch/arm64/Kbuild     | 2 ++
 arch/mips/Kbuild      | 2 ++
 arch/riscv/Kbuild     | 2 ++
 scripts/Makefile.dtbs | 3 +++
 6 files changed, 12 insertions(+), 1 deletion(-)
Makefile +1 -1
index 17cfa11ca716..85018d461575 100644
@@ -1494,7 +1494,7 @@ export CHECK_DTBS=y
 endif
 
 ifneq ($(CHECK_DTBS),)
-dtbs_prepare: dt_binding_schemas
+scripts_dtc: dt_binding_schemas
 endif
 
 dtbs_check: dtbs
arch/arm/Kbuild +2 -0
index 69de6b6243c7..af7dd53585c3 100644
@@ -10,5 +10,7 @@ obj-y				+= probes/
 obj-y				+= net/
 obj-y				+= crypto/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/arm64/Kbuild +2 -0
index 5bfbf7d79c99..9e9820af48c9 100644
@@ -5,5 +5,7 @@ obj-$(CONFIG_XEN)	+= xen/
 obj-$(subst m,y,$(CONFIG_HYPERV))	+= hyperv/
 obj-$(CONFIG_CRYPTO)	+= crypto/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/mips/Kbuild +2 -0
index e901bf554483..6125d00cdcef 100644
@@ -21,5 +21,7 @@ ifdef CONFIG_KVM
 obj-y += kvm/
 endif
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/riscv/Kbuild +2 -0
index 126fb738fc44..3cf7f84eb287 100644
@@ -7,5 +7,7 @@ obj-$(CONFIG_KVM) += kvm/
 
 obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
scripts/Makefile.dtbs +3 -0
index 2d321b813600..4d0d164df275 100644
@@ -14,7 +14,10 @@ dtb-y           := $(addprefix $(obj)/, $(dtb-y))
 multi-dtb-y     := $(addprefix $(obj)/, $(multi-dtb-y))
 real-dtb-y      := $(addprefix $(obj)/, $(real-dtb-y))
 
+ifneq ($(findstring /dts/,$(MAKECMDGOALS))$(findstring dtb,$(MAKECMDGOALS)),)
 always-y        += $(dtb-y)
+endif
+
 targets         += $(real-dtb-y)
 
 # dtbs-list
Signature · 1 line
2.51.0
#1 lore raw
Quoted 12 lines · Rob Herring (Arm)

It is useful to be able to build all the DTBs for a vendor. One can list all the .dts files in a directory and convert those to %.dtb targets, but that doesn't work for base+overlay DTB targets.

Adding the dts subdirectory is straight-forward, but building the DTBs should only happen for certain targets (dtbs, dtbs_check, %.dtb, %.dtbo, and the directory target(s)).

The 'scripts_dtc' rule doesn't really depend on 'dt_binding_schemas', but the directory target only depends on 'scripts' which depends on 'scripts_dtc'.

Quoted 6 lines

---
Please ack and I'll take this in the DT tree.

I don't really like looking at MAKECMDGOALS, but that's the only way I could come up with that works. Maybe someone knows a better way.

Yeah, I do worry that just looking for "dtb" in MAKECMDGOALS could result in some false positives but in the tree now, I only see one .c file that would trigger this logic, so maybe it is not that big of a deal?

  $ fd dtb
  arch/microblaze/boot/dts/linked_dtb.S
  arch/mips/include/asm/mach-loongson64/builtin_dtbs.h
  arch/um/kernel/dtb.c
  drivers/gpu/drm/ci/dtbs-check.sh
  scripts/Makefile.dtbinst
  scripts/Makefile.dtbs

Unfortunately, my Make-fu is pretty weak right now so I do not have any immediate suggestions but Nicolas might... otherwise, we could probably ride this for right now and either revert it or forward fix it if problems come up in further testing, since this does seem rather useful for folks working on device tree files.

Quoted 93 lines

v2:
- Convert arm, mips and riscv. The other DT enabled arches don't have vendor directories.
- Link to v1: https://lore.kernel.org/all/[email protected]/

---
 Makefile              | 2 +-
 arch/arm/Kbuild       | 2 ++
 arch/arm64/Kbuild     | 2 ++
 arch/mips/Kbuild      | 2 ++
 arch/riscv/Kbuild     | 2 ++
 scripts/Makefile.dtbs | 3 +++
 6 files changed, 12 insertions(+), 1 deletion(-)
Makefile +1 -1
index 17cfa11ca716..85018d461575 100644
@@ -1494,7 +1494,7 @@ export CHECK_DTBS=y
 endif
 
 ifneq ($(CHECK_DTBS),)
-dtbs_prepare: dt_binding_schemas
+scripts_dtc: dt_binding_schemas
 endif
 
 dtbs_check: dtbs
arch/arm/Kbuild +2 -0
index 69de6b6243c7..af7dd53585c3 100644
@@ -10,5 +10,7 @@ obj-y				+= probes/
 obj-y				+= net/
 obj-y				+= crypto/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/arm64/Kbuild +2 -0
index 5bfbf7d79c99..9e9820af48c9 100644
@@ -5,5 +5,7 @@ obj-$(CONFIG_XEN)	+= xen/
 obj-$(subst m,y,$(CONFIG_HYPERV))	+= hyperv/
 obj-$(CONFIG_CRYPTO)	+= crypto/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/mips/Kbuild +2 -0
index e901bf554483..6125d00cdcef 100644
@@ -21,5 +21,7 @@ ifdef CONFIG_KVM
 obj-y += kvm/
 endif
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/riscv/Kbuild +2 -0
index 126fb738fc44..3cf7f84eb287 100644
@@ -7,5 +7,7 @@ obj-$(CONFIG_KVM) += kvm/
 
 obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
scripts/Makefile.dtbs +3 -0
index 2d321b813600..4d0d164df275 100644
@@ -14,7 +14,10 @@ dtb-y           := $(addprefix $(obj)/, $(dtb-y))
 multi-dtb-y     := $(addprefix $(obj)/, $(multi-dtb-y))
 real-dtb-y      := $(addprefix $(obj)/, $(real-dtb-y))
 
+ifneq ($(findstring /dts/,$(MAKECMDGOALS))$(findstring dtb,$(MAKECMDGOALS)),)
 always-y        += $(dtb-y)
+endif
+
 targets         += $(real-dtb-y)
 
 # dtbs-list
Signature · 1 line
2.51.0
maintainer Tested-by Acked-by
#2 lore raw
Quoted 33 lines · Nathan Chancellor
Quoted 12 lines · Rob Herring (Arm)

It is useful to be able to build all the DTBs for a vendor. One can list all the .dts files in a directory and convert those to %.dtb targets, but that doesn't work for base+overlay DTB targets.

Adding the dts subdirectory is straight-forward, but building the DTBs should only happen for certain targets (dtbs, dtbs_check, %.dtb, %.dtbo, and the directory target(s)).

The 'scripts_dtc' rule doesn't really depend on 'dt_binding_schemas', but the directory target only depends on 'scripts' which depends on 'scripts_dtc'.

Quoted 6 lines

---
Please ack and I'll take this in the DT tree.

I don't really like looking at MAKECMDGOALS, but that's the only way I could come up with that works. Maybe someone knows a better way.

Yeah, I do worry that just looking for "dtb" in MAKECMDGOALS could result in some false positives but in the tree now, I only see one .c file that would trigger this logic, so maybe it is not that big of a deal?

  $ fd dtb
  arch/microblaze/boot/dts/linked_dtb.S
  arch/mips/include/asm/mach-loongson64/builtin_dtbs.h
  arch/um/kernel/dtb.c
  drivers/gpu/drm/ci/dtbs-check.sh
  scripts/Makefile.dtbinst
  scripts/Makefile.dtbs
Quoted 5 lines

Unfortunately, my Make-fu is pretty weak right now so I do not have any immediate suggestions but Nicolas might... otherwise, we could probably ride this for right now and either revert it or forward fix it if problems come up in further testing, since this does seem rather useful for folks working on device tree files.

well, evaluating MAKECMDGOALS does not look that bad to me. But I'd rather like to reduce the use of findstring, see below.

Quoted 84 lines
Quoted 84 lines

v2:
- Convert arm, mips and riscv. The other DT enabled arches don't have vendor directories.
- Link to v1: https://lore.kernel.org/all/[email protected]/

---
 Makefile              | 2 +-
 arch/arm/Kbuild       | 2 ++
 arch/arm64/Kbuild     | 2 ++
 arch/mips/Kbuild      | 2 ++
 arch/riscv/Kbuild     | 2 ++
 scripts/Makefile.dtbs | 3 +++
 6 files changed, 12 insertions(+), 1 deletion(-)
Makefile +1 -1
index 17cfa11ca716..85018d461575 100644
@@ -1494,7 +1494,7 @@ export CHECK_DTBS=y
 endif
 
 ifneq ($(CHECK_DTBS),)
-dtbs_prepare: dt_binding_schemas
+scripts_dtc: dt_binding_schemas
 endif
 
 dtbs_check: dtbs
arch/arm/Kbuild +2 -0
index 69de6b6243c7..af7dd53585c3 100644
@@ -10,5 +10,7 @@ obj-y				+= probes/
 obj-y				+= net/
 obj-y				+= crypto/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/arm64/Kbuild +2 -0
index 5bfbf7d79c99..9e9820af48c9 100644
@@ -5,5 +5,7 @@ obj-$(CONFIG_XEN)	+= xen/
 obj-$(subst m,y,$(CONFIG_HYPERV))	+= hyperv/
 obj-$(CONFIG_CRYPTO)	+= crypto/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/mips/Kbuild +2 -0
index e901bf554483..6125d00cdcef 100644
@@ -21,5 +21,7 @@ ifdef CONFIG_KVM
 obj-y += kvm/
 endif
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
arch/riscv/Kbuild +2 -0
index 126fb738fc44..3cf7f84eb287 100644
@@ -7,5 +7,7 @@ obj-$(CONFIG_KVM) += kvm/
 
 obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/
 
+subdir-y += boot/dts
+
 # for cleaning
 subdir- += boot
scripts/Makefile.dtbs +0 -0
index 2d321b813600..4d0d164df275 100644
@@ -14,7 +14,10 @@ dtb-y           := $(addprefix $(obj)/, $(dtb-y))
 multi-dtb-y     := $(addprefix $(obj)/, $(multi-dtb-y))
 real-dtb-y      := $(addprefix $(obj)/, $(real-dtb-y))
 
Quoted 1 line

scripts/Makefile.dtbs dtb-y := $(addprefix $(obj)/, $(dtb-y)) · line 17

Quoted 1 line
scripts/Makefile.dtbs +1 -0
+ifneq ($(findstring /dts/,$(MAKECMDGOALS))$(findstring dtb,$(MAKECMDGOALS)),)

Using '$(filter )' instead of '$(findstring )' reduces the risk of false positives, e.g.:

dtb-targets := %/dts %.dtb %.dtbo dtbs dtbs_check
ifneq ($(findstring /dts/,$(MAKECMDGOALS))$(filter $(dtb-targets),$(MAKECMDGOALS)),)

With (something like) that:

But [1] seems to break this patch.

[1]: https://lore.kernel.org/linux-kbuild/[email protected]

Kind regards,
Nicolas

maintainer Acked-by
#3 lore raw
Quoted 5 lines · Nicolas Schier

Using '$(filter )' instead of '$(findstring )' reduces the risk of false positives, e.g.:

dtb-targets := %/dts %.dtb %.dtbo dtbs dtbs_check
ifneq ($(findstring /dts/,$(MAKECMDGOALS))$(filter $(dtb-targets),$(MAKECMDGOALS)),)

Oh yeah, that would seem to clear up my concerns.

Quoted 3 lines

With (something like) that:

Agreed.

Quoted 3 lines

But [1] seems to break this patch.

[1]: https://lore.kernel.org/linux-kbuild/[email protected]

Yeah, that will need to be coordinated, I cc'd Rob on that change for him to take a look as well.

Cheers,
Nathan