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of: Add support for linking device tree blobs into vmlinux

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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>
This commit is contained in:
Dirk Brandewie
2010-12-22 11:57:26 -08:00
committed by Grant Likely
parent cfb13c5db0
commit aab94339cd
3 changed files with 49 additions and 2 deletions
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13
include/asm-generic/vmlinux.lds.h
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@@ -67,7 +67,8 @@
* Align to a 32 byte boundary equal to the
* alignment gcc 4.5 uses for a struct
*/
#define STRUCT_ALIGN() . = ALIGN(32)
#define STRUCT_ALIGNMENT 32
#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT)
/* The actual configuration determine if the init/exit sections
* are handled as text/data or they can be discarded (which
@@ -146,6 +147,13 @@
#define TRACE_SYSCALLS()
#endif
#define KERNEL_DTB() \
STRUCT_ALIGN(); \
VMLINUX_SYMBOL(__dtb_start) = .; \
*(.dtb.init.rodata) \
VMLINUX_SYMBOL(__dtb_end) = .;
/* .data section */
#define DATA_DATA \
*(.data) \
@@ -468,7 +476,8 @@
MCOUNT_REC() \
DEV_DISCARD(init.rodata) \
CPU_DISCARD(init.rodata) \
MEM_DISCARD(init.rodata)
MEM_DISCARD(init.rodata) \
KERNEL_DTB()
#define INIT_TEXT \
*(.init.text) \