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    SubjectRe: [PATCH 1/4] of: Add support for linking device tree blobs into vmlinux
    On 22.12.2010 20:57, dirk.brandewie@gmail.com wrote:
    > From: Dirk Brandewie<dirk.brandewie@gmail.com>
    >
    > 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>

    Hi,

    you can add
    Acked-by: Michal Marek <mmarek@suse.cz>
    but I thing this series should go through the tip tree, as your primary
    target seems to be x86 and patch 2/4 depends on the ce4100 code that is
    only in tip.

    Michal

    > ---
    > Documentation/kbuild/makefiles.txt | 15 +++++++++++++++
    > include/asm-generic/vmlinux.lds.h | 13 +++++++++++--
    > scripts/Makefile.lib | 23 +++++++++++++++++++++++
    > 3 files changed, 49 insertions(+), 2 deletions(-)
    >
    > diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
    > index 0ef00bd..86e3cd0 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
    >
    > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
    > index bd69d79..05cbad0 100644
    > --- a/include/asm-generic/vmlinux.lds.h
    > +++ b/include/asm-generic/vmlinux.lds.h
    > @@ -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) \
    > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
    > index 4c72c11..7df8eb5 100644
    > --- a/scripts/Makefile.lib
    > +++ b/scripts/Makefile.lib
    > @@ -200,6 +200,29 @@ quiet_cmd_gzip = GZIP $@
    > cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9> $@) || \
    > (rm -f $@ ; false)
    >
    > +# DTC
    > +# ---------------------------------------------------------------------------
    > +
    > +# Generate an assembly file to wrap the output of the device tree compiler
    > +quiet_cmd_dt_S_dtb= DTB $@
    > +cmd_dt_S_dtb= \
    > +( \
    > + echo '\#include<asm-generic/vmlinux.lds.h>'; \
    > + echo '.section .dtb.init.rodata,"a"'; \
    > + echo '.balign STRUCT_ALIGNMENT'; \
    > + echo '.global __dtb_$(*F)_begin'; \
    > + echo '__dtb_$(*F)_begin:'; \
    > + echo '.incbin "$<" '; \
    > + echo '__dtb_$(*F)_end:'; \
    > + echo '.global __dtb_$(*F)_end'; \
    > + echo '.balign STRUCT_ALIGNMENT'; \
    > +)> $@
    > +
    > +$(obj)/%.dtb.S: $(obj)/%.dtb
    > + $(call cmd,dt_S_dtb)
    > +
    > +quiet_cmd_dtc = DTC $@
    > + cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) $<
    >
    > # Bzip2
    > # ---------------------------------------------------------------------------



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