[Lenny400] LetuxOS on SD card for MIPS JZ4780 CI20
paul at boddie.org.uk
Sat Apr 13 21:48:05 CEST 2019
On Saturday 13. April 2019 20.02.15 H. Nikolaus Schaller wrote:
> Hi Paul,
> I have spent some minutes on adapting LetuxOS to the CI20 so that we
> eventually can create bootable SD cards with "makesd".
> I have a first success:
> Net: dm9000
> Hit any key to stop autoboot: 0
> 4058380 bytes read in 673 ms (5.8 MiB/s)
> ## Booting kernel from Legacy Image at 88000000 ...
> Image Name: Linux-4.19.34-letux-l400+
> Image Type: MIPS Linux Kernel Image (gzip compressed)
> Data Size: 4058316 Bytes = 3.9 MiB
> Load Address: 80010000
> Entry Point: 8065f750
> Verifying Checksum ... OK
> Uncompressing Kernel Image ... OK
> Starting kernel ...
The details certainly look quite reasonable.
> This is a self-made cross-compiled SPL + U-Boot on SD card based on the
> description at https://elinux.org/CI20_Dev_Zone#Building_uboot_from_sources
I noticed that the CONFIG contains settings enabled for ARM/OMAP and wondered
whether this was actually the configuration used.
> There are two issues so far:
> 1. the console output of the SPL (and U-Boot) seems to be mostly missing and
> starts not before the "Net: dm9000" line or "Hit any key"
What is the SPL? I don't remember ever seeing anything before those messages.
One thing which I did encounter was some confusion about which UART was being
used. Ultimately, I used UART0, but I do wonder if U-Boot might use another
UART early on.
Here is a page on the topic:
What I did need to do was to change /etc/inittab to enable ttyS0 for a login
prompt to appear on UART0, but that is with the kernel starting...
> 2. Kernel is not starting
> well, I have not found how this U-Boot wants to handle the device-tree so
> this is very expected. And I am not 100% sure if the installed kernel is
> the jz4730/Mipsbook or the jz4780/CI20 kernel (unfortunately, there is no
> Multiarch for Ingenic so we can't build universal kernels)
I don't know what Multiarch means in this context, but I would think that just
bundling the right device tree binary would be enough. Otherwise, the SoCs are
pretty similar, and I can't immediately think of anything that would require
different kernels for the different devices, at least if device tree works as
Still, this looks promising!
More information about the Lenny400