[PATCH 2/4] of: Add support for linking device tree blobs into vmlinux

[Grant Likely]

On Thu, Nov 11, 2010 at 04:03:48PM -0800, dirk.brandewie at gmail.com wrote:
> From: Dirk Brandewie <dirk.brandewie at gmail.com>
> 
> This patch adds support for linking device tree blobs into
> vmlinux. The device tree blobs are placed in the init.data
> section.
> 
> Signed-off-by: Dirk Brandewie <dirk.brandewie at gmail.com>
> ---
>  include/asm-generic/vmlinux.lds.h |   13 ++++++++++++-
>  init/Kconfig                      |    7 +++++++
>  scripts/Makefile.lib              |   14 ++++++++++++++
>  3 files changed, 33 insertions(+), 1 deletions(-)
> 
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index bd69d79..c8f600e 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -146,6 +146,16 @@
>  #define TRACE_SYSCALLS()
>  #endif
>  
> +#ifdef CONFIG_KERNEL_DTB
> +#define KERNEL_DTB							\

To match other definitions in this file, this should be defined with
parentheses: #define KERNEL_DTB()

> +	. = ALIGN(32);							\
> +	VMLINUX_SYMBOL(__dtb_start) = .;				\
> +	*(.dtb)			       					\

I wonder if .meminit.rodata.dtb be a better section name.  Could use
some input from more experienced kernel hackers here.  hpa, what say
you?

Also, inconsistent indentation (mixed tabs and spaces).

> +	VMLINUX_SYMBOL(__dtb_end) = .;
> +#else
> +#define KERNEL_DTB
> +#endif
> +

Does this need to be wrapped with CONFIG_KERNEL_DTB?  Is there any
downside to including these sections unconditionally?

>  /* .data section */
>  #define DATA_DATA							\
>  	*(.data)							\
> @@ -468,7 +478,8 @@
>  	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/init/Kconfig b/init/Kconfig
> index 88c1046..fddfc0f 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1083,6 +1083,13 @@ config PCI_QUIRKS
>            bugs/quirks. Disable this only if your target machine is
>            unaffected by PCI quirks.
>  
> +config KERNEL_DTB
> +       bool "Support linking a device tree blob into vmlinux"
> +       default n
> +       help
> +         This option provides support for adding a device tree blob(s)
> +	 directly to vmlinux

Inconsistent indentation.  I'm also not convinced that this Kconfig
symbol is really needed (as commented on above).

> +
>  config SLUB_DEBUG
>  	default y
>  	bool "Enable SLUB debugging support" if EMBEDDED
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 4c72c11..c4487b2 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -200,6 +200,20 @@ quiet_cmd_gzip = GZIP    $@
>  cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9 > $@) || \
>  	(rm -f $@ ; false)
>  
> +# DTC
> +#  ---------------------------------------------------------------------------
> +$(obj)/%.dtb.S: $(obj)/%.dtb FORCE
> +	@echo '.section .dtb,"a"' > $@
> +	@echo '.global __dtb_$(*F)_begin' >> $@
> +	@echo '__dtb_$(*F)_begin:' >> $@
> +	@echo '.incbin "$<" ' >> $@
> +	@echo '__dtb_$(*F)_end:' >> $@
> +	@echo '.global __dtb_$(*F)_end' >> $@
> +
> +DTC = $(objtree)/scripts/dtc/dtc
> +
> +quiet_cmd_dtc = DTC	$@
> +      cmd_dtc = $(DTC) -O dtb -o $(obj)/$*.dtb -b 0  $(dtstree)/$*.dts

As already mentioned; need to rationalized these rule additions with
the changes made in patch #1.

g.