Right way to boot on Vontar X3 / HK1 on microSD (possible no boot)

[AndNovAtor]

Device Information | 设备信息

• SOC: S095x3
• Model: Vontar X3 [like HK1]

Armbian Version | 系统版本

• Kernel Version: 6.6.53 - 6.6.74 / 6.1.119 - 6.1.127 [+ 6.6.15]
• Release: noble
• amlogic-s9xxx-armbian release version: 24.11 - 25.02 [+ 24.2]
• dtb file: meson-sm1-x96-max-plus.dtb (+ meson-sm1-x96-max-plus-100m.dtb by default)

Describe the bug | 问题描述
No boot ("freeze") with "latest" images on Vontar X3 WITHOUT changing BOOT.

Please provide a detailed description of the issue and, if necessary, attach a screenshot.

I have (had?) "problems" with boot on my Vontar X3 "tv box" (like HK1 Box), on microSD.

I used 24.2 version of this project (thx a lot btw). Both jammy and noble worked for me (I used jammy).

In last year I tried more "recent" version, with no success. Boot "freezed" on tv box logo (after one "blink").

I tried both jammy and noble, both 6.1.* and 6.6.* versions - no success.
I tried to move old dtb file to new installation on boot partition (with "replace") - no success.

I tried to replace from 0x15000000 to 0x13000000 in boot.ini - of course, no success (because in 24.2 version it was 0x13000000 for initrd_addr, but yeah, I know it's stupid replace).

!! BUT THEN I found on some page this text (translated):

The second point is that you need to find a file called u-boot.ext in the root of BOOT. If there is no such file, then you need to take the u-boot-s905x3.bin file and rename it to the u-boot.ext

I tried to do so - and FINALLY my 25.02 (with noble, 6.6.74) booted successfully.
(But on 24.2 there are no u-boot.ext, still I boot this version successfully without modifications).

So, my question - how to boot 24.11 and above versions "correctly"? Does some "modifications" needed to release versions?
(And what is u-boot.ext?)

[ophub]

It is not required by default when using the latest version, the kernel has been patched. Whether it is a new version or an old version, adding u-boot.ext will have no negative effects.

[AndNovAtor]

not required

But why 22.02 works without it, and > 22.09 works only with it on my Vontar X3? u-boot specificity in board?

Also, if it's REALY required for Vontar X3 now... should it noted somewhere (in docs, etc)? Or I missed something? I can be wrong...

(As I sayed, simply load img to microSD - no boot)