Hi,
You mentioned that there is no uboot on your board, it just boot up kernel and rootfs directly. That is not making sense, as far as I know, on i.NX233 EVK, you should init enternal DRAM, power etc. first, then load the kernel to DRAM. And this initialization of DRAM and power is called bootlets.
So you didn't see any bootlets on the release package? See below, that is our bootlets did, it will load power_prep and dram_prep to init power and dram, then load linux zImage. So, for splash screen, you can load a picture's raw data to DRAM, then in this bootlets(its function is same as bootloader), init LCDIF and display this picture.
You can find such bootlet first, then look into the linux.bd, it has the load & call command that are recognized by ROM, ROM will execute these orders. If I am right, this git should can be get from the release package.
linux-bootlets.git
linux.bd:
2 options {
3 driveTag = 0x00;
4 flags = 0x01;
5 }
6 sources {
7 power_prep="./power_prep/power_prep";
8 sdram_prep="./boot_prep/boot_prep";
9 linux_prep="./linux_prep/output-target/linux_prep";
10 zImage="./zImage";
11 }
12
13 section (0) {
14
15 //----------------------------------------------------------
16 // Power Supply initialization
17 //----------------------------------------------------------
18 load power_prep;
19 call power_prep;
20
21 //----------------------------------------------------------
22 // SDRAM initialization
23 //----------------------------------------------------------
24 load sdram_prep;
25 call sdram_prep;
26
27 //----------------------------------------------------------
28 // Prepare to boot Linux
29 //----------------------------------------------------------
30 load linux_prep;
31 call linux_prep;
32
33 //----------------------------------------------------------
34 // Load ans start Linux kernel
35 //----------------------------------------------------------
36 load zImage > 0x40008000;
37 jump linux_prep;
38 }
