Commit 978928e4 authored by Maxime Ripard's avatar Maxime Ripard Committed by Thomas Petazzoni
Browse files

Add support for appended device tree blobs for arm 



This patch adds support for the ARM-only appended device tree
mechanism present in the kernel.

This option allows to add at the end of the kernel image the
device tree blob so that we can still boot device tree enabled
kernels with old bootloaders.

This patch also adds the needed logic to genereate such an image
when building zImages or uImages, also adding the necessary parts
to rebuild the uImage.

Signed-off-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
parent 902609fb

linux/Config.in

+33 −0
Original line number Diff line number Diff line
@@ -140,6 +140,13 @@ config BR2_LINUX_KERNEL_UIMAGE 
	depends on BR2_arm || BR2_armeb || BR2_bfin || BR2_powerpc || BR2_avr32 || BR2_sh || BR2_sh64

	select BR2_LINUX_KERNEL_UBOOT_IMAGE



config BR2_LINUX_KERNEL_APPENDED_UIMAGE

	bool "uImage with appended DT"

	depends on BR2_arm || BR2_armeb

	select BR2_LINUX_KERNEL_DTS_SUPPORT

	select BR2_LINUX_KERNEL_APPENDED_DTB

	select BR2_LINUX_KERNEL_UBOOT_IMAGE



config BR2_LINUX_KERNEL_BZIMAGE

	bool "bzImage"

	depends on BR2_i386 || BR2_x86_64
@@ -148,6 +155,12 @@ config BR2_LINUX_KERNEL_ZIMAGE 
	bool "zImage"

	depends on BR2_arm || BR2_armeb || BR2_powerpc || BR2_sparc || BR2_sh || BR2_sh64 || BR2_xtensa



config BR2_LINUX_KERNEL_APPENDED_ZIMAGE

	bool "zImage with appended DT"

	depends on BR2_arm || BR2_armeb

	select BR2_LINUX_KERNEL_DTS_SUPPORT

	select BR2_LINUX_KERNEL_APPENDED_DTB



config BR2_LINUX_KERNEL_VMLINUX_BIN

	bool "vmlinux.bin"

	depends on BR2_mips || BR2_mipsel || BR2_sh || BR2_sh64
@@ -187,6 +200,26 @@ config BR2_LINUX_KERNEL_DTS_SUPPORT 


if BR2_LINUX_KERNEL_DTS_SUPPORT



# We have mainly three cases when it comes to device tree support:

#   1) We don't want any support at all. Then the ..DTS_SUPPORT

#      variable won't be set

#   2) We want device tree support, so we need the user to enter

#      the device tree name or the the path to the custom device

#      he uses, but the kernel abstracts this from us and only

#      build an image that looks like a regular kernel image. In

#      this case, we only need to derive the kernel image name from

#      the given device tree name, and all the rest is as usual

#   3) We want device tree support, but the kernel requires us to

#      build the device tree blob separately. In this case, some

#      more logic will be needed.

# The variable below address the second case, were you only want

# limited actions from buildroot.

config BR2_LINUX_KERNEL_DTB_IS_SELF_BUILT

	bool



config BR2_LINUX_KERNEL_APPENDED_DTB

	bool



choice

	prompt "Device tree source"

	default BR2_LINUX_KERNEL_USE_INTREE_DTS

linux/linux.mk

+36 −1
Original line number Diff line number Diff line
@@ -58,6 +58,13 @@ else ifeq ($(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),y) 
KERNEL_DTS_NAME = $(basename $(notdir $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)))

endif



ifeq ($(BR2_LINUX_KERNEL_APPENDED_DTB),y)

ifneq ($(words $(KERNEL_DTS_NAME)),1)

$(error Kernel with appended device tree needs exactly one DTS source.\

  Check BR2_LINUX_KERNEL_INTREE_DTS_NAME or BR2_LINUX_KERNEL_CUSTOM_DTS_PATH.)

endif

endif



ifeq ($(BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM),y)

LINUX_IMAGE_NAME=$(call qstrip,$(BR2_LINUX_KERNEL_IMAGE_TARGET_NAME))

else
@@ -68,10 +75,14 @@ LINUX_IMAGE_NAME=vmImage 
else

LINUX_IMAGE_NAME=uImage

endif

else ifeq ($(BR2_LINUX_KERNEL_APPENDED_UIMAGE),y)

LINUX_IMAGE_NAME=uImage

else ifeq ($(BR2_LINUX_KERNEL_BZIMAGE),y)

LINUX_IMAGE_NAME=bzImage

else ifeq ($(BR2_LINUX_KERNEL_ZIMAGE),y)

LINUX_IMAGE_NAME=zImage

else ifeq ($(BR2_LINUX_KERNEL_APPENDED_ZIMAGE),y)

LINUX_IMAGE_NAME=zImage

else ifeq ($(BR2_LINUX_KERNEL_VMLINUX_BIN),y)

LINUX_IMAGE_NAME=vmlinux.bin

else ifeq ($(BR2_LINUX_KERNEL_VMLINUX),y)
@@ -81,6 +92,12 @@ LINUX_IMAGE_NAME=vmlinuz 
endif

endif



ifeq ($(BR2_LINUX_KERNEL_APPENDED_DTB),y)

LINUX_IMAGE_TARGET=zImage

else

LINUX_IMAGE_TARGET=$(LINUX_IMAGE_NAME)

endif



# Compute the arch path, since i386 and x86_64 are in arch/x86 and not

# in arch/$(KERNEL_ARCH). Even if the kernel creates symbolic links

# for bzImage, arch/i386 and arch/x86_64 do not exist when copying the
@@ -161,10 +178,13 @@ define LINUX_CONFIGURE_CMDS 
		$(call KCONFIG_SET_OPT,CONFIG_UEVENT_HELPER_PATH,\"/sbin/mdev\",$(@D)/.config))

	$(if $(BR2_PACKAGE_SYSTEMD),

		$(call KCONFIG_ENABLE_OPT,CONFIG_CGROUPS,$(@D)/.config))

	$(if $(BR2_LINUX_KERNEL_APPENDED_DTB),

		$(call KCONFIG_ENABLE_OPT,CONFIG_ARM_APPENDED_DTB,$(@D)/.config))

	yes '' | $(TARGET_MAKE_ENV) $(MAKE1) $(LINUX_MAKE_FLAGS) -C $(@D) oldconfig

endef



ifeq ($(BR2_LINUX_KERNEL_DTS_SUPPORT),y)

ifeq ($(BR2_LINUX_KERNEL_DTB_IS_SELF_BUILT),)

define LINUX_BUILD_DTB

	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(KERNEL_DTS_NAME).dtb

endef
@@ -172,17 +192,32 @@ define LINUX_INSTALL_DTB 
	cp $(KERNEL_ARCH_PATH)/boot/$(KERNEL_DTS_NAME).dtb $(BINARIES_DIR)/

endef

endif

endif



ifeq ($(BR2_LINUX_KERNEL_APPENDED_UIMAGE),y)

define LINUX_APPEND_DTB

	cat $(KERNEL_ARCH_PATH)/boot/$(KERNEL_DTS_NAME).dtb >> $(KERNEL_ARCH_PATH)/boot/zImage

	# We need to generate the uImage here after that so that the uImage is

	# generated with the right image size.

	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) uImage

endef

else ifeq ($(BR2_LINUX_KERNEL_APPENDED_ZIMAGE),y)

define LINUX_APPEND_DTB

	cat $(KERNEL_ARCH_PATH)/boot/$(KERNEL_DTS_NAME).dtb >> $(KERNEL_ARCH_PATH)/boot/zImage

endef

endif



# Compilation. We make sure the kernel gets rebuilt when the

# configuration has changed.

define LINUX_BUILD_CMDS

	$(if $(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),

		cp $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) $(KERNEL_ARCH_PATH)/boot/dts/)

	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_IMAGE_NAME)

	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_IMAGE_TARGET)

	@if grep -q "CONFIG_MODULES=y" $(@D)/.config; then 	\

		$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) modules ;	\

	fi

	$(LINUX_BUILD_DTB)

	$(LINUX_APPEND_DTB)

endef