path: root/Documentation/kbuild/makefiles.txt
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authorDirk Brandewie <dirk.brandewie@gmail.com>2010-12-22 11:57:26 -0800
committerGrant Likely <grant.likely@secretlab.ca>2010-12-23 14:43:00 -0700
commitaab94339cd85d726abeae78fc02351fc1910e6a4 (patch)
tree25d434a1dec4f758a9938e621dc1516f7a788521 /Documentation/kbuild/makefiles.txt
parentMerge commit 'v2.6.37-rc7' into devicetree/next (diff)
of: Add support for linking device tree blobs into vmlinux
This patch adds support for linking device tree blob(s) into vmlinux. Modifies asm-generic/vmlinux.lds.h to add linking .dtb sections into vmlinux. To maintain compatiblity with the of/fdt driver code platforms MUST copy the blob to a non-init memory location before the kernel frees the .init.* sections in the image. Modifies scripts/Makefile.lib to add a kbuild command to compile DTS files to device tree blobs and a rule to create objects to wrap the blobs for linking. STRUCT_ALIGNMENT is defined in vmlinux.lds.h for use in the rule to create wrapper objects for the dtb in Makefile.lib. The STRUCT_ALIGN() macro in vmlinux.lds.h is modified to use the STRUCT_ALIGNMENT definition. The DTB's are placed on 32 byte boundries to allow parsing the blob with driver/of/fdt.c during early boot without having to copy the blob to get the structure alignment GCC expects. A DTB is linked in by adding the DTB object to the list of objects to be linked into vmlinux in the archtecture specific Makefile using obj-y += foo.dtb.o Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com> Acked-by: Michal Marek <mmarek@suse.cz> [grant.likely@secretlab.ca: cleaned up whitespace inconsistencies] Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'Documentation/kbuild/makefiles.txt')
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 0ef00bd6e54d..86e3cd0d26a0 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -1136,6 +1136,21 @@ When kbuild executes, the following steps are followed (roughly):
resulting in the target file being recompiled for no
obvious reason.
+ dtc
+ Create flattend device tree blob object suitable for linking
+ into vmlinux. Device tree blobs linked into vmlinux are placed
+ in an init section in the image. Platform code *must* copy the
+ blob to non-init memory prior to calling unflatten_device_tree().
+ Example:
+ #arch/x86/platform/ce4100/Makefile
+ clean-files := *dtb.S
+ DTC_FLAGS := -p 1024
+ obj-y += foo.dtb.o
+ $(obj)/%.dtb: $(src)/%.dts
+ $(call cmd,dtc)
--- 6.7 Custom kbuild commands