Debian on ds218play (rtl1296 cpu) - work in progress

Hi,

back again. As I have finished my tests with the ds214 and it working as my "productive" NAS now I wanted to see whether I can get my ds218play working. This is a bit different, as it uses an Realtek rtl1296 cpu.

I managed to connect the UART to it and stop at u-boot. Attached you will find some logs for that one.

I can load files via tftp, but at the moment I am searching for a matching kernel + device tree + initrd + rootfs. Any ideas where to start?
There is some branch in u-boot which looks promising for the dts: https://github.com/afaerber/linux/blob/rtd1295-next/arch/arm64/boot/dts/realtek/rtd1296-ds418.dts The ds418 has the same cpu on it. Edit: oops, that was not u-boot but the kernel device tree

Very interestingly it uses a 2-staged bootloader with two different u-boots. Looks like a trusted-firmware system, but apparently the device is not locked.

And yes - I know that fiddling around with the device can brick it ;)
BTW: is there a similar way to boot via serial as on the kirkwood devices?

regards,
Martin



Edited 2 time(s). Last edit at 08/07/2023 11:59AM by lonestar.

I did some further tests and even found the original kernel config of synology in their gpl sources.
Unfortunately when I use this config on an 6.0.8 kernel the kernel gets quite big (>20MB)

u-boot seems to only support the typical 8MB image, as I get "Loading Kernel Image ... Image too large: increase CONFIG_SYS_BOOTM_LEN".
As I want to avoid having to flash the u-boot instances I will have to downsize the kernel.

So far I have gotten down to 8.84MiB.

My current workflow:
- compile kernel and create uImage with the dtb from the kernel tree (rtd1296-ds418.dtb)
- in the first u-boot use tftp to load the uImage to ram. I currently ignore the initrd as I am not there yet.
- the I use bootr to switch to the second u-boot.
- in the second u-boot I call bootm to boot the image.

Note that the first u-boot does not support bootm and the second one does not support tftp.

I attach my current kernel config, where I hopefully didn't deactivate anything I need and where I still need to find further stuff that can be safely disabled. So if anyone wants to take a look and has some ideas, I am happy :)

.config_downsizing is my current state
rtd1296_kernel_config is the original from the gpl source.

regards,
Martin

I spent a little time looking at some similar devices running a RTD1195 and RTD1619 (Buffalo Linkstation LS500 and LS700). I ran into the reference to that two stage u-boot needed for the device-tree's in the mainline kernel but hadn't gotten around to finding it yet.

I don't have much to add at this point but I'm glad to see someone taking a look!