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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>
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@ -1136,6 +1136,21 @@ When kbuild executes, the following steps are followed (roughly):
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resulting in the target file being recompiled for no
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resulting in the target file being recompiled for no
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obvious reason.
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obvious reason.
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dtc
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Create flattend device tree blob object suitable for linking
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into vmlinux. Device tree blobs linked into vmlinux are placed
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in an init section in the image. Platform code *must* copy the
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blob to non-init memory prior to calling unflatten_device_tree().
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Example:
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#arch/x86/platform/ce4100/Makefile
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clean-files := *dtb.S
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DTC_FLAGS := -p 1024
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obj-y += foo.dtb.o
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$(obj)/%.dtb: $(src)/%.dts
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$(call cmd,dtc)
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--- 6.7 Custom kbuild commands
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--- 6.7 Custom kbuild commands
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@ -67,7 +67,8 @@
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* Align to a 32 byte boundary equal to the
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* Align to a 32 byte boundary equal to the
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* alignment gcc 4.5 uses for a struct
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* alignment gcc 4.5 uses for a struct
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*/
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*/
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#define STRUCT_ALIGN() . = ALIGN(32)
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#define STRUCT_ALIGNMENT 32
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#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT)
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/* The actual configuration determine if the init/exit sections
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/* The actual configuration determine if the init/exit sections
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* are handled as text/data or they can be discarded (which
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* are handled as text/data or they can be discarded (which
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@ -146,6 +147,13 @@
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#define TRACE_SYSCALLS()
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#define TRACE_SYSCALLS()
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#endif
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#endif
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#define KERNEL_DTB() \
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STRUCT_ALIGN(); \
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VMLINUX_SYMBOL(__dtb_start) = .; \
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*(.dtb.init.rodata) \
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VMLINUX_SYMBOL(__dtb_end) = .;
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/* .data section */
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/* .data section */
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#define DATA_DATA \
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#define DATA_DATA \
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*(.data) \
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*(.data) \
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@ -468,7 +476,8 @@
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MCOUNT_REC() \
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MCOUNT_REC() \
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DEV_DISCARD(init.rodata) \
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DEV_DISCARD(init.rodata) \
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CPU_DISCARD(init.rodata) \
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CPU_DISCARD(init.rodata) \
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MEM_DISCARD(init.rodata)
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MEM_DISCARD(init.rodata) \
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KERNEL_DTB()
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#define INIT_TEXT \
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#define INIT_TEXT \
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*(.init.text) \
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*(.init.text) \
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@ -200,6 +200,29 @@ quiet_cmd_gzip = GZIP $@
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cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9 > $@) || \
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cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9 > $@) || \
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(rm -f $@ ; false)
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(rm -f $@ ; false)
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# DTC
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# ---------------------------------------------------------------------------
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# Generate an assembly file to wrap the output of the device tree compiler
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quiet_cmd_dt_S_dtb= DTB $@
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cmd_dt_S_dtb= \
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( \
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echo '\#include <asm-generic/vmlinux.lds.h>'; \
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echo '.section .dtb.init.rodata,"a"'; \
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echo '.balign STRUCT_ALIGNMENT'; \
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echo '.global __dtb_$(*F)_begin'; \
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echo '__dtb_$(*F)_begin:'; \
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echo '.incbin "$<" '; \
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echo '__dtb_$(*F)_end:'; \
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echo '.global __dtb_$(*F)_end'; \
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echo '.balign STRUCT_ALIGNMENT'; \
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) > $@
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$(obj)/%.dtb.S: $(obj)/%.dtb
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$(call cmd,dt_S_dtb)
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quiet_cmd_dtc = DTC $@
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cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) $<
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# Bzip2
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# Bzip2
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# ---------------------------------------------------------------------------
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# ---------------------------------------------------------------------------
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