Re: [PATCH 2/2] env: point fdt address to the fdt in a bloblist

[Tom Rini <trini@konsulko.com>]

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On Thu, Mar 27, 2025 at 04:13:17PM -0700, Raymond Mao wrote:

> Point fdt_addr to the fdt embedded in the bloblist since fdt_addr
> is a default address for bootefi, bootm and booti to look for the
> device tree when launching the kernel.
> 
> Signed-off-by: Raymond Mao <raymond.mao@linaro.org>
> ---
>  env/common.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/env/common.c b/env/common.c
> index a58955a4f42..a38e5d107a8 100644
> --- a/env/common.c
> +++ b/env/common.c
> @@ -16,6 +16,7 @@
>  #include <asm/global_data.h>
>  #include <linux/printk.h>
>  #include <linux/stddef.h>
> +#include <mapmem.h>
>  #include <search.h>
>  #include <errno.h>
>  #include <malloc.h>
> @@ -368,6 +369,18 @@ int env_get_default_into(const char *name, char *buf, unsigned int len)
>  	return env_get_from_linear(default_environment, name, buf, len);
>  }
>  
> +static int env_update_fdt_addr_from_bloblist(void)
> +{
> +	/*
> +	 * fdt_addr is by default used by booti, bootm and bootefi,
> +	 * thus set it to point to the fdt embedded in a bloblist if it exists.
> +	 */
> +	if (!CONFIG_IS_ENABLED(BLOBLIST) || gd->fdt_src != FDTSRC_BLOBLIST)
> +		return 0;
> +
> +	return env_set_hex("fdt_addr", (uintptr_t)map_to_sysmem(gd->fdt_blob));
> +}

This part is fine with me and makes enough sense, we can't do this
immediately so we need some check to know to do it later.

>  void env_set_default(const char *s, int flags)
>  {
>  	if (s) {
> @@ -392,6 +405,10 @@ void env_set_default(const char *s, int flags)
>  
>  	gd->flags |= GD_FLG_ENV_READY;
>  	gd->flags |= GD_FLG_ENV_DEFAULT;
> +
> +	/* This has to be done after GD_FLG_ENV_READY is set */
> +	if (env_update_fdt_addr_from_bloblist())
> +		pr_err("Failed to set fdt_addr to point at DTB\n");
>  }

I don't know this is the right spot. This won't work when for example
the environment is valid but stored in a file on FAT (or whatever) will
it?

-- 
Tom

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