When Falcon Mode is enabled, spl_start_uboot() function must be defined. If this function returns 0 then SPL should start the kernel, if it returns 1 then U-Boot must be started.
When spl_start_uboot() returns 1, then U-Boot must be loaded, and as far as I can tell spl_image->os should be set to IH_OS_U_BOOT before: if (os_takes_devicetree(spl_image->os)) { ret = spl_fit_append_fdt(spl_image, info, sector, &ctx); in common/spl/spl_fit.c/ int spl_load_simple_fit(...) this is not the case currently, and the loading fails. If set manually spl_image->os = IH_OS_U_BOOT, it works fine. The only place I could see where it could be set is a few lines above in: if (!spl_fit_image_get_os(ctx.fit, node, &spl_image->os)) debug("Image OS is %s\n", genimg_get_os_name(spl_image->os)); else if (!IS_ENABLED(CONFIG_SPL_OS_BOOT)) spl_image->os = IH_OS_U_BOOT; but the second "if" does not execute, obviously (since we are in falcon, CONFIG_SPL_OS_BOOT is enabled). I see a few options, but I am not sure how best to fix this: 1) add something like: else if (!IS_ENABLED(CONFIG_SPL_OS_BOOT) || spl_start_uboot()) spl_image->os = IH_OS_U_BOOT; but this would mean calling spl_start_uboot() twice, requiring it to return the same value. It works in my case. 2) set spl_image->os to IH_OS_U_BOOT when the spl_start_uboot() is called the first time, in: common/spl/spl_mmc.c/spl_mmc_do_fs_boot(..) - in several places: #ifdef CONFIG_SPL_FS_FAT if (!spl_start_uboot()) { err = spl_load_image_fat_os(spl_image, bootdev, mmc_get_blk_desc(mmc), ... #ifdef CONFIG_SPL_FS_EXT4 if (!spl_start_uboot()) { err = spl_load_image_ext_os(spl_image, bootdev, mmc_get_blk_desc(mmc), ... Any insight on how to proceed? I've implemented spl_start_uboot() to decide on whether to boot the kernel or the U-Boot based on key presses on the console. Thank you, Elena.