From aab94339cd85d726abeae78fc02351fc1910e6a4 Mon Sep 17 00:00:00 2001 From: Dirk Brandewie Date: Wed, 22 Dec 2010 11:57:26 -0800 Subject: 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 Acked-by: Michal Marek [grant.likely@secretlab.ca: cleaned up whitespace inconsistencies] Signed-off-by: Grant Likely --- Documentation/kbuild/makefiles.txt | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'Documentation/kbuild') diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 0ef00bd6e54..86e3cd0d26a 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 -- cgit v1.2.3