[PATCH v2] powerpc/bootwrapper: Add documentation of boot wrapper targets

[Anatolij Gustschin]

Grant Likely wrote:
> From: Grant Likely <grant.likely at secretlab.ca>
> 
> There have been many questions on and off the mailing list about how
> exactly the bootwrapper is used for embedded targets.  Add some
> documentation and help text to try and clarify the system.
> 
> Signed-off-by: Grant Likely <grant.likely at secretlab.ca>

<snip>

> diff --git a/Documentation/powerpc/bootwrapper.txt b/Documentation/powerpc/bootwrapper.txt
> new file mode 100644
> index 0000000..a03d73c
> --- /dev/null
> +++ b/Documentation/powerpc/bootwrapper.txt
> @@ -0,0 +1,141 @@
> +The PowerPC boot wrapper
> +------------------------
> +Copyright (C) Secret Lab Technologies Ltd.
> +
> +PowerPC image targets compresses and wraps the kernel image (vmlinux) with
> +a boot wrapper to make it usable by the system firmware.  There is no
> +standard PowerPC firmware interface, so the boot wrapper is designed to
> +be adaptable for each kind of image that needs to be built.
> +
> +The boot wrapper can be found in the arch/powerpc/boot/ directory.  The
> +Makefile in that directory has targets for all the available image types.
> +The different image types are used to support all of the various firmware
> +interfaces found on PowerPC platforms.  OpenFirmware is the most commonly
> +used firmare type on general purpose PowerPC systems from Apple, IBM and

typo, s/firmare/firmware/

<snip>

> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index b7d4c4c..754c7eb 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -169,12 +169,25 @@ bootwrapper_install %.dtb:
>  	$(Q)$(MAKE) ARCH=ppc64 $(build)=$(boot) $(patsubst %,$(boot)/%,$@)
>  
>  define archhelp
> -  @echo '* zImage          - Compressed kernel image (arch/$(ARCH)/boot/zImage.*)'
> +  @echo '* zImage          - Build default images selected by kernel config'
> +  @echo '  zImage.*        - Compressed kernel image (arch/$(ARCH)/boot/zImage.*)'
> +  @echo '  uImage          - U-Book native image format'

typo, s/U-Book/U-Boot/

> +  @echo '  cuImage.<dt>    - Backwards compatible U-Boot image for older'
> +  @echo '                    versions which do not support device trees'
> +  @echo '  dtbImage.<dt>   - zImage with an embedded device tree blob'
> +  @echo '  simpleImage.<dt> - Firmware independant image.'

typo, s/independant/independent/

Cheers,
Anatolij