[RFC] [PATCH V2] Adding DTB to architecture independent vmlinux

[Dirk Brandewie]

Here is V2 of the patch.

The support for linking in the DTB is now a config option. The location
of the config option is completely arbitrary.

The name of the added section has been changed to avoid possible collision
with the powerpc linkage of the DTB into the final image.

ATM this patch would add a redundant/unused section (without name collision) to 
the microblaze if configured in since I do not understand why the padding added 
to _fdt_start.

This has only been tested on x86.

Comments Suggestions?

--Dirk

of: add support for linking platform dtb into vmlinux

From: Dirk Brandewie <dirk.brandewie at gmail.com>

This patch adds support for linking a device tree blob into
vmlinux. The platform DTB to be built and linked into the kernel is
specified by passing PLATFORM_DTB=<platform name> to make.

The command:
make PLATFORM_DTB=ce4100

will link the device tree blob into vmlinux

Signed-off-by: Dirk Brandewie <dirk.brandewie at gmail.com>
---
  arch/x86/kernel/Makefile          |   15 +++++++++++++++
  include/asm-generic/vmlinux.lds.h |   15 +++++++++++++++
  init/Kconfig                      |    7 +++++++
  scripts/Makefile.lib              |    7 +++++++
  5 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 3068e1e..0f5eb1d 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -120,6 +120,21 @@ obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o
  obj-$(CONFIG_SWIOTLB)			+= pci-swiotlb.o
  obj-$(CONFIG_X86_OF)			+= prom.o

+ifeq ($(CONFIG_KERNEL_DTB),y)
+ifneq ($(PLATFORM_DTB),)
+obj-y += $(PLATFORM_DTB).dtb.o
+endif
+endif
+
+dtstree	:= $(srctree)/arch/x86/boot/dts
+
+$(obj)/%.dtb: $(dtstree)/%.dts
+	$(call if_changed,dtc)
+
+$(obj)/%.dtb.S: $(obj)/%.dtb
+	@echo '.section .dtb,"a"' > $@
+	@echo '.incbin "$<" ' >> $@
+
  ###
  # 64 bit specific files
  ifeq ($(CONFIG_X86_64),y)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 8a92a17..b18123a 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -146,6 +146,19 @@
  #define TRACE_SYSCALLS()
  #endif

+#ifdef CONFIG_KERNEL_DTB
+#define KERNEL_DTB							\
+	. = ALIGN(4);							\
+	.dtb : AT(ADDR(.dtb) - LOAD_OFFSET) {				\
+		VMLINUX_SYMBOL(__dtb_start) = .;			\
+		*(.dtb)							\
+		VMLINUX_SYMBOL(__dtb_end) = .;				\
+	}
+
+#else
+#define KERNEL_DTB
+#endif
+
  /* .data section */
  #define DATA_DATA							\
  	*(.data)							\
@@ -245,6 +258,8 @@
  		VMLINUX_SYMBOL(__end_pci_fixups_suspend) = .;		\
  	}								\
  									\
+	KERNEL_DTB							\
+									\
  	/* Built-in firmware blobs */					\
  	.builtin_fw        : AT(ADDR(.builtin_fw) - LOAD_OFFSET) {	\
  		VMLINUX_SYMBOL(__start_builtin_fw) = .;			\
diff --git a/init/Kconfig b/init/Kconfig
index 2de5b1c..4a8802e 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1055,6 +1055,13 @@ config PCI_QUIRKS
            bugs/quirks. Disable this only if your target machine is
            unaffected by PCI quirks.

+config KERNEL_DTB
+       bool "Support linking a device tree blob into vmlinux"
+       default n
+       help
+         This option provides support for adding a device tree blob
+	 directly to vmlinux
+
  config SLUB_DEBUG
  	default y
  	bool "Enable SLUB debugging support" if EMBEDDED
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 54fd1b7..ce32644 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -207,6 +207,13 @@ quiet_cmd_gzip = GZIP    $@
  cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9 > $@) || \
  	(rm -f $@ ; false)

+# DTC
+#  ---------------------------------------------------------------------------
+
+DTC = $(objtree)/scripts/dtc/dtc
+
+quiet_cmd_dtc = DTC	$@
+      cmd_dtc = $(DTC) -O dtb -o $(obj)/$*.dtb -b 0 -p 1024 $(dtstree)/$*.dts

  # Bzip2
  # ---------------------------------------------------------------------------