Hi Simon,
On Wed, Aug 30, 2023 at 12:05:01PM -0600, Simon Glass wrote:
> Standard passage provides for a bloblist to be passed from one firmware
> phase to the next. That can be used to pass the devicetree along as well.
> Add an option to support this.
>
> Tests for this will be added as part of the Universal Payload work.
>
> Signed-off-by: Simon Glass <s...@chromium.org>
> ---
>
> common/bloblist.c | 2 ++
> doc/develop/devicetree/control.rst | 3 ++
> dts/Kconfig | 8 ++++++
> include/bloblist.h | 5 ++++
> include/fdtdec.h | 3 +-
> lib/fdtdec.c | 44 ++++++++++++++++++++++--------
> 6 files changed, 52 insertions(+), 13 deletions(-)
>
> diff --git a/common/bloblist.c b/common/bloblist.c
> index 6f2a4577708..b07ede11cfe 100644
> --- a/common/bloblist.c
> +++ b/common/bloblist.c
> @@ -48,9 +48,11 @@ static struct tag_name {
> { BLOBLISTT_ACPI_TABLES, "ACPI tables for x86" },
> { BLOBLISTT_SMBIOS_TABLES, "SMBIOS tables for x86" },
> { BLOBLISTT_VBOOT_CTX, "Chrome OS vboot context" },
> + { BLOBLISTT_CONTROL_FDT, "Control FDT" },
>
> /* BLOBLISTT_PROJECT_AREA */
> { BLOBLISTT_U_BOOT_SPL_HANDOFF, "SPL hand-off" },
> + { BLOBLISTT_VBE, "VBE" },
> { BLOBLISTT_U_BOOT_VIDEO, "SPL video handoff" },
>
> /* BLOBLISTT_VENDOR_AREA */
> diff --git a/doc/develop/devicetree/control.rst
> b/doc/develop/devicetree/control.rst
> index cbb65c9b177..56e00090166 100644
> --- a/doc/develop/devicetree/control.rst
> +++ b/doc/develop/devicetree/control.rst
> @@ -108,6 +108,9 @@ If CONFIG_OF_BOARD is defined, 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 CONFIG_OF_BLOBLIST is defined, the devicetree comes from a bloblist passed
> +from a previous stage.
> +
Is this bloblist in the format described in the firmware handoff [0] ?
> +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 early phase so that
> + U-Boot can read it.
> +
I dont think this is a good idea. We used to have 4-5 different options
here, which we tried to clean up and ended up with two very discrete
options. Why do we have to reintroduce a new one? Doesn't that bloblist
have a header of some sort? The bloblist literally comes from a previous
stage bootloader which is what OF_BOARD is here for. So why can't we just
read the header and figure out if the magic of the bloblist matches?
> 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/include/bloblist.h b/include/bloblist.h
> index 080cc46a126..e16d122f4fb 100644
> --- a/include/bloblist.h
> +++ b/include/bloblist.h
> @@ -103,6 +103,11 @@ enum bloblist_tag_t {
> BLOBLISTT_ACPI_TABLES = 0x104, /* ACPI tables for x86 */
> BLOBLISTT_SMBIOS_TABLES = 0x105, /* SMBIOS tables for x86 */
> BLOBLISTT_VBOOT_CTX = 0x106, /* Chromium OS verified boot context */
> + /*
[...]
>
[0] https://github.com/FirmwareHandoff/firmware_handoff
Thanks
/Ilias
