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| author | Dirk Brandewie <dirk.brandewie@gmail.com> | 2010-12-22 11:57:26 -0800 |
|---|---|---|
| committer | Grant Likely <grant.likely@secretlab.ca> | 2010-12-23 14:43:00 -0700 |
| commit | aab94339cd85d726abeae78fc02351fc1910e6a4 (patch) | |
| tree | 25d434a1dec4f758a9938e621dc1516f7a788521 /Documentation/kbuild | |
| parent | cfb13c5db08c90311a5defdde9a0328ee788cca5 (diff) | |
| download | lwn-aab94339cd85d726abeae78fc02351fc1910e6a4.tar.gz lwn-aab94339cd85d726abeae78fc02351fc1910e6a4.zip | |
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')
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 15 |
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 |