[PATCH 1/2] environment: support DT-compatible-specific overlays

[Marco Felsch]

Hi Ahmad,

On 26-04-13, Ahmad Fatoum wrote:
> Board-specific environments are registered from board code via
> defaultenv_append_directory(), but this isn't possible when using
> CONFIG_DEFAULT_ENVIRONMENT_PATH with an external environment.
> 
> Add support for a match.of_compatible/ directory convention within
> the default environment. Subdirectories named after DT root compatible
> strings are overlaid onto /env from most generic to most specific
> after the default environment is loaded. The match.of_compatible/
> directory is removed afterwards to keep /env clean.

That's a nice feature!

> Example layout in CONFIG_DEFAULT_ENVIRONMENT_PATH:
> 
>   barebox-defaultenv/
>     nv/boot.default
>     match.of_compatible/
>       fsl,imx8mm/
>         nv/boot.default
>       fsl,imx8mq-evk/
		^
        fsl,imx8mm-evk/ ?

>         nv/boot.default
> 
> For compatible = "fsl,imx8mm-evk", "fsl,imx8mm":
>   1. fsl,imx8mm/     overlay applied first  (most generic)
>   2. fsl,imx8mm-evk/ overlay applied second (most specific)
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum at barebox.org>
> ---
>  common/startup.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++

Can we have a Documentation update for this mechanism please incl. the
search order? :)

Regards,
  Marco


>  1 file changed, 47 insertions(+)
> 
> diff --git a/common/startup.c b/common/startup.c
> index 2e2b5f820fe9..e630033e3505 100644
> --- a/common/startup.c
> +++ b/common/startup.c
> @@ -46,6 +46,7 @@
>  #include <pbl/handoff-data.h>
>  #include <libfile.h>
>  #include <fuzz.h>
> +#include <of.h>
>  
>  extern initcall_t __barebox_initcalls_start[], __barebox_early_initcalls_end[],
>  		  __barebox_initcalls_end[];
> @@ -95,6 +96,50 @@ void autoload_external_env(bool endis)
>  }
>  #endif
>  
> +static void env_merge_of_compat_overlays(const char *dir)
> +{
> +	struct device_node *root;
> +	const char *compat;
> +	struct stat s;
> +	char *ofdir, *src;
> +	int count;
> +
> +	root = of_get_root_node();
> +	if (!root)
> +		return;
> +
> +	ofdir = xasprintf("%s/match.of_compatible", dir);
> +
> +	if (stat(ofdir, &s) || !S_ISDIR(s.st_mode))
> +		goto out;
> +
> +	count = of_property_count_strings(root, "compatible");
> +
> +	/*
> +	 * Apply overlays from most generic to most specific, so that
> +	 * more specific entries take precedence.
> +	 */
> +	for (int i = count - 1; i >= 0; i--) {
> +		if (of_property_read_string_index(root, "compatible",
> +						  i, &compat))
> +			continue;
> +
> +		src = xasprintf("%s/%s", ofdir, compat);
> +
> +		if (stat(src, &s) == 0 && S_ISDIR(s.st_mode)) {
> +			pr_debug("Applying '%s'-compatible environment overlay\n",
> +				 compat);
> +			copy_recursive(src, dir, 0);
> +		}
> +
> +		free(src);
> +	}
> +
> +	unlink_recursive(ofdir, NULL);
> +out:
> +	free(ofdir);
> +}
> +
>  static int load_environment(void)
>  {
>  	const char *default_environment_path;
> @@ -115,6 +160,8 @@ static int load_environment(void)
>  		pr_info("external environment support %s. Using default environment\n",
>  			IS_ENABLED(CONFIG_ENV_HANDLING) ? "disallowed" : "disabled");
>  
> +	env_merge_of_compat_overlays("/env");
> +
>  	nvvar_load();
>  
>  	return 0;
> -- 
> 2.47.3
> 
> 
> 

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