Patchwork [1/4] of: Add support for linking device tree blobs into vmlinux

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Submitter dirk.brandewie@gmail.com
Date Dec. 22, 2010, 7:57 p.m.
Message ID <1293047849-26078-2-git-send-email-dirk.brandewie@gmail.com>
Download mbox | patch
Permalink /patch/76442/
State Accepted, archived
Delegated to: Grant Likely
Headers show

Comments

dirk.brandewie@gmail.com - Dec. 22, 2010, 7:57 p.m.
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>
---
 Documentation/kbuild/makefiles.txt |   15 +++++++++++++++
 include/asm-generic/vmlinux.lds.h  |   13 +++++++++++--
 scripts/Makefile.lib               |   23 +++++++++++++++++++++++
 3 files changed, 49 insertions(+), 2 deletions(-)
Michal Marek - Dec. 22, 2010, 10:36 p.m.
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
>   # ---------------------------------------------------------------------------
Geert Uytterhoeven - Dec. 23, 2010, 6:14 a.m.
2010/12/22 Michal Marek <mmarek@suse.cz>:
> 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.

If the two lines

+# device tree blob
+obj-$(CONFIG_X86_INTEL_CE) += ce4100.dtb.o

are removed, patch 2/4 no longer depends on the ce4100 code.
The summary and description for that patch don't mention anything
about ce4100 anyway.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
Grant Likely - Dec. 23, 2010, 9:42 p.m.
On Wed, Dec 22, 2010 at 11:57:26AM -0800, 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>

merged, thanks.

g.

> ---
>  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
>  # ---------------------------------------------------------------------------
> -- 
> 1.7.2.3
> 
> _______________________________________________
> devicetree-discuss mailing list
> devicetree-discuss@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/devicetree-discuss
Grant Likely - Dec. 23, 2010, 9:44 p.m.
On Thu, Dec 23, 2010 at 07:14:20AM +0100, Geert Uytterhoeven wrote:
> 2010/12/22 Michal Marek <mmarek@suse.cz>:
> > 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.
> 
> If the two lines
> 
> +# device tree blob
> +obj-$(CONFIG_X86_INTEL_CE) += ce4100.dtb.o
> 
> are removed, patch 2/4 no longer depends on the ce4100 code.
> The summary and description for that patch don't mention anything
> about ce4100 anyway.

I'd like to take this through the dt tree.  I'll drop the ce4100 hunk
when I merge it.

g.

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

Patch

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
 # ---------------------------------------------------------------------------