[Letux-kernel] Successfully booting LetuxOS on Star64 (RISCV) board

[H. Nikolaus Schaller]

> Google AI tells that the badaddr ffffffd600000000 is too systmatic...
> And, that the boot loader and OpenSBI v1.2 could be too old for modern kernels.
> Especially for handling memory size (the board has 8GB but kernel tells it has 4GB).
> 
> A final suggestion was to reduce to mem=2G. WIth that, the boot process crashes after approx. 2 seconds.
> And the final final hint was about checking the power supply...
> 
> Which all means this ends the "fun" session for now. It is changing into "a lot of work" to be done (i.e. have our own LetuxOS Boot system and hope it helps).

Well, I had some more discussions with the Googe AI Mode...

And finally after presenting full boot logs it turned out what the problem is.

RISCV boot includes something called OpenSBI. This is sometimes called "firmware".
Its function seems to be sort of a "Hardware abstraction layer" which allows the manufacturer to improve things without breaking user-space code.
It is compiled into U-Boot and it seems to be code installed at the fixed memory address 0x40000000.
After it is loaded U-Boot and the Kernel can use it.

But the kernel assumed that RAM is starting at 0x40000000 and fully available.
So at some point it did start to overwrite OpenSBI...

This is different from all the ARM and MIPS SoC I know where there is some SRAM (or even the cache)
used during boot and RAM is under full control of U-Boot or Linux-

The trick proposed by the AI Mode was to add tweaks to the FDT and to the kernel bootcmd.

This was simple to add to our boot.scr:

https://git.goldelico.com/?p=letux-uboot.git;a=blob;f=Letux/boot-scr/boot-star64.txt;h=28c92df6c8317bc3d91f50cd812bd5e4b7e8916e;hb=e910826905738c57ae4f2dbdd86fbdf21652ca9a
https://download.goldelico.com/letux-u-boot/Star64/latest/

The board is now running some heavy load (debootstrapping Debian for RISCV) and has not crashed for one hour. Let's see what happens :)

BR,
Nikolaus

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