This is a follow-up to a previous thread here. For those who didn't see it, I have this board which is made by the Chinese manufacturer "Firefly", using a Rockchip RK3588 (another Chinese product, the latest in a line that's been around for over a decade or so of ARM SoCs but importantly, not yet supported fully in the most recent kernels, and I suspect that will be a problem at some point and I'll have to somehow switch in the modified, slightly dated 5.10.66 kernel instance that is provided with the board there). It's a nice little board that has a small standard desktop form-factor, and the performance while running Android looked good enough as a low power consumption and x86-alternative replacement to my old 2018 era big, heavy, hard-to-transport x86 machine. Moreover, because of both the architecture, the Android-running capability, and the fact it has a M.2 slot you can put a 4G/5G LTE network card into it (something I actually want to do at some point), I affectionately call it a "Deskphone" 
And what I'm trying to do right now is get Gentoo working, after it was suggested in the previous thread about failed graphics support on Ubuntu, to try a different Linux distribution.
Anyway, I downloaded and extracted the .iso to a usb stick and I'm trying to boot it via U-Boot, and this is happening. I've encountered this problem before when trying to load GRUB in a different context, and I suspect the Gentoo USB stick tries to boot a GRUB instance. I don't know what to do about it. In particular, note the "Scanning disk ramdisk-ro.blk ...." part just when it chokes - I dug through the GRUB source code and found that apparently what's happening here is that that device ("ramdisk-ro.blk") doesn't exist, yet it tries to scan it anyway. Not sure if this is a bug in GRUB, U-Boot, or what, and if there's a workaround or not. What do you suggest here?

And what I'm trying to do right now is get Gentoo working, after it was suggested in the previous thread about failed graphics support on Ubuntu, to try a different Linux distribution.
Anyway, I downloaded and extracted the .iso to a usb stick and I'm trying to boot it via U-Boot, and this is happening. I've encountered this problem before when trying to load GRUB in a different context, and I suspect the Gentoo USB stick tries to boot a GRUB instance. I don't know what to do about it. In particular, note the "Scanning disk ramdisk-ro.blk ...." part just when it chokes - I dug through the GRUB source code and found that apparently what's happening here is that that device ("ramdisk-ro.blk") doesn't exist, yet it tries to scan it anyway. Not sure if this is a bug in GRUB, U-Boot, or what, and if there's a workaround or not. What do you suggest here?
Code:
=> load usb 0:1 ${kernel_addr_r} efi.img
=================begin===================
2949120 bytes read in 279 ms (10.1 MiB/s)
(some details omitted for privacy reasons)
=> load mmc 0:0f ${fdt_addr_r} rk3588-firefly-itx-3588j.dtb
=================begin===================
153955 bytes read in 3 ms (48.9 MiB/s)
=> help bootefi
bootefi - Boots an EFI payload from memory
Usage:
bootefi <image address> [fdt address]
- boot EFI payload stored at address <image address>.
If specified, the device tree located at <fdt address> gets
exposed as EFI configuration table.
=> bootefi ${kernel_addr_r} ${fdt_addr_r}
## Starting EFI application at 00400000 ...
Scanning disk ramdisk-ro.blk...
"Synchronous Abort" handler, esr 0x96000010
* Reason: Exception from a Data abort, from current exception level
* PC = 00000000002b5e84
* LR = 0000000000245e4c
* SP = 00000000eb9f9780
* ESR_EL2 = 0000000096000010
* Reloc Off = 00000000edb2d000
x0 : 00000000eb9f9980 x1 : 0000000000000000
x2 : 0000000000000200 x3 : 0000000000000000
x4 : 0000000000000200 x5 : 0000000000000020
x6 : 000000000000000d x7 : 00000000ede0ba58
x8 : 00000000eb9f9c38 x9 : 0000000000000008
x10: 00000000ffffffd0 x11: 000000000a100000
x12: 0000000000000000 x13: 0000000000000200
x14: 000000000000000c x15: 0000000000000021
x16: 00000000edd72e20 x17: 00000000ebdcf2c0
x18: 00000000eb9ffcf0 x19: 0000000000000001
x20: 00000000ebd29f60 x21: 00000000ebd29f60
x22: 00000000ede27082 x23: 00000000ede164b8
x24: 00000000ede164cd x25: 0000000000000000
x26: 0000000000000000 x27: 0000000000000000
x28: 00000000ebdd3cd0 x29: 00000000eb9f9960
Call trace:
PC: [< 002b5e84 >]
LR: [< 00245e4c >]
Stack:
[< 002b5e84 >]
[< 00231c50 >]
[< 0022f8d0 >]
[< 0022fe28 >]
[< 0029ab08 >]
[< 00208ff0 >]
[< 00209294 >]
[< 0022e3b8 >]
[< 00217904 >]
[< 00217ab8 >]
[< 00217208 >]
[< 002177bc >]
[< 00217ab8 >]
[< 00217fec >]
[< 0022da7c >]
[< 00215fe4 >]
[< 002187d4 >]
[< 0029ea00 >]
[< 00218b98 >]
[< 00201e10 >]
Copy info from "Call trace..." to a file(eg. dump.txt), and run
command in your U-Boot project: ./scripts/stacktrace.sh dump.txt
Resetting CPU ...
### ERROR ### Please RESET the board ###