Hi Simon,
On Fri, 28 Mar 2025 at 11:44, Simon Glass <s...@chromium.org> wrote:
>
> Add an option which indicates that the devicetree comes from the
> bloblist.
>
> After discussions with Tom, it seems we are comfortable with introducing
> this option, ensuring of course that the transfer list is properly
> supported.
>
> Signed-off-by: Simon Glass <s...@chromium.org>
> ---
>
> doc/develop/devicetree/control.rst | 3 ++
> dts/Kconfig | 8 ++++
> lib/fdtdec.c | 66 ++++++++++++------------------
> 3 files changed, 38 insertions(+), 39 deletions(-)
>
> diff --git a/doc/develop/devicetree/control.rst
> b/doc/develop/devicetree/control.rst
> index 0233945f8b6..d80f4d420a9 100644
> --- a/doc/develop/devicetree/control.rst
> +++ b/doc/develop/devicetree/control.rst
> @@ -137,6 +137,9 @@ If `OF_BOARD` is selected by Kconfig, a board-specific
> routine will provide the
> devicetree at runtime, for example if an earlier bootloader stage creates
> it and passes it to U-Boot.
>
> +If `OF_BLOBLIST` is defined, the devicetree comes from a bloblist passed
> +from a previous stage.
> +
> If `BLOBLIST` is selected by Kconfig, the devicetree may come from a bloblist
> passed from a previous stage, if present.
>
> diff --git a/dts/Kconfig b/dts/Kconfig
> index 6a5141b56e9..04359a4d7b2 100644
> --- a/dts/Kconfig
> +++ b/dts/Kconfig
> @@ -167,6 +167,14 @@ config OF_INITIAL_DTB_READONLY
> If initial DTB for DT control is read-only (e.g. points to
> memory-mapped flash memory), then set this option.
>
> +config OF_BLOBLIST
> + bool "DTB is provided by a bloblist"
> + help
> + Select this to read the devicetree from the bloblist. This allows
> + using a bloblist to transfer the devicetree between U-Boot phases.
> + The devicetree is stored in the bloblist by an earlier phase so that
> + U-Boot can read it.
> +
> config OF_BOARD
> bool "Provided by the board (e.g a previous loader) at runtime"
> default y if SANDBOX || OF_HAS_PRIOR_STAGE
> diff --git a/lib/fdtdec.c b/lib/fdtdec.c
> index f09c9926a7a..833f8aca3ce 100644
> --- a/lib/fdtdec.c
> +++ b/lib/fdtdec.c
> @@ -1689,55 +1689,43 @@ void fdtdec_setup_embed(void)
>
> int fdtdec_setup(void)
I think a better idea is to use BLOBLIST_PASSAGE_MANDATORY, see below
pseudo code:
```
if (IS_ENABLED(CONFIG_OF_BOARD)) {
/* get fdt from board */
}
/* allow fdtcontroladdr to override it */
if (CONFIG_IS_ENABLED(BLOBLIST) && ... ) {
/* try to find fdt from bloblist */
if (CONFIG_IS_ENABLED(BLOBLIST_PASSAGE_MANDATORY) {
if (no_fdt_in_bloblist)
return ERROR;
/* override fdt with the one from bloblist */
}
}
```
Regards,
Raymond
> {
> - int ret = -ENOENT;
> + int ret;
>
> - /*
> - * If allowing a bloblist, check that first. There was discussion
> about
> - * adding an OF_BLOBLIST Kconfig, but this was rejected.
> - *
> - * The necessary test is whether the previous phase passed a bloblist,
> - * not whether this phase creates one.
> - */
> - if (CONFIG_IS_ENABLED(BLOBLIST) &&
> - (xpl_prev_phase() != PHASE_TPL ||
> - IS_ENABLED(CONFIG_TPL_BLOBLIST))) {
> + if (CONFIG_IS_ENABLED(OF_BLOBLIST)) {
> ret = bloblist_maybe_init();
> - if (!ret) {
> - gd->fdt_blob = bloblist_find(BLOBLISTT_CONTROL_FDT,
> 0);
> - if (gd->fdt_blob) {
> - gd->fdt_src = FDTSRC_BLOBLIST;
> - log_debug("Devicetree is in bloblist at %p\n",
> - gd->fdt_blob);
> - ret = 0;
> - } else {
> - log_debug("No FDT found in bloblist\n");
> - ret = -ENOENT;
> - }
> + if (ret)
> + return ret;
> + gd->fdt_blob = bloblist_find(BLOBLISTT_CONTROL_FDT, 0);
> + if (!gd->fdt_blob) {
> + printf("Not FDT found in bloblist\n");
> + bloblist_show_list();
> + return -ENOENT;
> }
> - }
> -
> - /* Otherwise, the devicetree is typically appended to U-Boot */
> - if (ret) {
> + gd->fdt_src = FDTSRC_BLOBLIST;
> + bloblist_show_list();
> + log_debug("Devicetree is in bloblist at %p\n", gd->fdt_blob);
> + } else {
> if (IS_ENABLED(CONFIG_OF_SEPARATE)) {
> gd->fdt_blob = fdt_find_separate();
> gd->fdt_src = FDTSRC_SEPARATE;
> } else { /* embed dtb in ELF file for testing / development */
> - fdtdec_setup_embed();
> + gd->fdt_blob = dtb_dt_embedded();
> + gd->fdt_src = FDTSRC_EMBED;
> }
> - }
>
> - /* Allow the board to override the fdt address. */
> - if (IS_ENABLED(CONFIG_OF_BOARD)) {
> - void *blob;
> + /* Allow the board to override the fdt address. */
> + if (IS_ENABLED(CONFIG_OF_BOARD)) {
> + void *blob;
>
> - blob = (void *)gd->fdt_blob;
> - ret = board_fdt_blob_setup(&blob);
> - if (ret) {
> - if (ret != -EEXIST)
> - return ret;
> - } else {
> - gd->fdt_src = FDTSRC_BOARD;
> - gd->fdt_blob = blob;
> + blob = (void *)gd->fdt_blob;
> + ret = board_fdt_blob_setup(&blob);
> + if (ret) {
> + if (ret != -EEXIST)
> + return ret;
> + } else {
> + gd->fdt_src = FDTSRC_BOARD;
> + gd->fdt_blob = blob;
> + }
> }
> }
>
> --
> 2.43.0
>
