Re: [PATCH v7] arm: Add Kconfig entry to select CONFIG_DTB_FILE

[Julien Grall <julien@xxxxxxx>]

Hi Michal,

On 15/03/2021 09:23, Michal Orzel wrote:
> Currently in order to link existing DTB into Xen image
> we need to either specify option CONFIG_DTB_FILE on the
> command line or manually add it into .config.
> Add Kconfig entry: CONFIG_DTB_FILE
> to be able to provide the path to DTB we want to embed
> into Xen image. If no path provided - the dtb will not
> be embedded.
>
> Remove the line: AFLAGS-y += -DCONFIG_DTB_FILE=\"$(CONFIG_DTB_FILE)\"
> as it is not needed since Kconfig will define it in a header
> with all the other config options.
>
> Make a change in the linker script from:
> _sdtb = .;
> to:
> PROVIDE(_sdtb = .);
> to avoid creation of _sdtb if there is no reference to it.
This means that if someone is using #ifdef CONFIG_DTB_FILE rather than 
.ifnes, _sdtb will get defined.
The difference between two is quite subttle and can be easily missed 
during review.
How about defining _sdtb in dtb.S? With that approach, we would get a 
compiler error if someone protect _sdtb with #ifdef rather than .ifnes.
Cheers,

--
Julien Grall