[PATCH 0/6] Integrator devicetree support
Arnd Bergmann
arnd at arndb.de
Mon Aug 20 00:05:24 EST 2012
On Saturday 18 August 2012, Linus Walleij wrote:
> Since we already have CONFIG_USE_OF I think
> CONFIG_USE_ATAGS is more apropriate, but I get the
> idea.
There is both CONFIG_USE_OF and CONFIG_OF. The former is what
a platform selects and it turns on a few other options as well,
while the latter is the one that you typically check in #ifdef.
We might need both of them for ATAG as well, but I think if
we have just one, CONFIG_ATAGS or CONFIG_ATAG would be nicer
because it's slightly shorter.
> So it begins like this:
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index e91c7cd..0764ef7 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1907,6 +1907,12 @@ endmenu
>
> menu "Boot options"
>
> +config USE_ATAGS
> + bool "ATAGS support"
> + default y
> + help
> + Include support for ATAGS-based machine descriptions.
> +
> config USE_OF
> bool "Flattened Device Tree support"
> select OF
> @@ -2110,6 +2116,7 @@ config KEXEC
>
> config ATAGS_PROC
> bool "Export atags in procfs"
> + depends on USE_ATAGS
> depends on KEXEC
> default y
> help
>
> But then we hit #ifdeffing and compiling out a lot of dangerous stuff
> in arch/arm/kernel and then I get the creeps. I can try, but I think
> this is typical Nico territory for example...
We don't have to enclose every single usage of ATAGS with this, but
I think it's helpful in platforms that you want to migrate away
from ATAG to DT-only. I think we should also use this method in
mach-ux500, for instance.
Putting MACHINE_START and DT_MACHINE_START inside of CONFIG_ATAG
and CONFIG_OF respectively would help ensure that we don't
accidentally build support for a board that cannot work.
Arnd
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