[PATCH v5 7/7] doc: Add a warning about using RELOC_ADDR_TOP

[Simon Glass]

Hi Ilias,

On 2026-06-04T07:37:05, Ilias Apalodimas <ilias.apalodimas at linaro.org> wrote:
> doc: Add a warning about using RELOC_ADDR_TOP
>
> Since devices that can't DMA above 4GiB will misbehave with this option
> enabled add a warning on the documentation.
>
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
>
> doc/develop/memory.rst | 6 ++++++
>  1 file changed, 6 insertions(+)

Reviewed-by: Simon Glass <sjg at chromium.org>

nits/suggestions below

> diff --git a/doc/develop/memory.rst b/doc/develop/memory.rst
> @@ -110,6 +110,12 @@ U-Boot Proper Flow
>
>        This follows the same as in SPL flow. In board_init_f(), a part of memory
>        is reserved at the end of RAM (see reserve_* functions in init_sequence_f)
> +   #. Relocation address
> +      By default U-Boot will try to relocate below the 4GiB boundary. If
> +      RELOC_ADDR_TOP is enabled U-Boot will look into the dram bank config of
> +      gd->dram[] and try to relocate to the highest available bank. Use this
> +      with caution as devices that can only DMA below 4GiB will misbehave
> +      since their buffers may be allocated above the 32-bit boundary.

Can you check the rendering here? It seems that the title will run on
to the text?

Also text only covers the default and RELOC_ADDR_TOP, but does not
mention that boards can still override via board_get_usable_ram_top().
Worth a sentence, since that is the other half of the new behaviour
from patch 5.

Regards,
Simon