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

[Simon Glass]

Hi Raymond,

On Thu, 27 Mar 2025 at 17:13, Raymond Mao <raymond.mao at linaro.org> 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.

I wonder if we can drop use of that environment variable at some
point? It seems strange to set a variable to gd->fdt_addr only to use
it later. Why not just use gd->fdt_addr ?

I hit this in the bootstd conversion but wasn't sure what to do. So
much confusion.

I see quite a few boards setting this variable in their environment.
So this patch would override that setting, wouldn't it? It's just not
clear what any of this means.

So I think at this point we should update the code to use the internal
control FDT directly.

>
> Signed-off-by: Raymond Mao <raymond.mao at 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;

This is just too messy, sorry.

> +
> +       return env_set_hex("fdt_addr", (uintptr_t)map_to_sysmem(gd->fdt_blob));
> +}
> +
>  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");
>  }
>
>  /* [re]set individual variables to their value in the default environment */
> --
> 2.25.1
>

Regards,
Simon



On Thu, 27 Mar 2025 at 17:13, Raymond Mao <raymond.mao at linaro.org> 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 at 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));
> +}
> +
>  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");
>  }
>
>  /* [re]set individual variables to their value in the default environment */
> --
> 2.25.1
>