[Letux-kernel] MIPS-Generic Kernel on CI20

[H. Nikolaus Schaller]

I have compared the SPL code generated from both trees and there aren't many
differences. Funnily the binary size is exactly the same but the reason may be some
padding:

iMac:U-Boot hns$ ls -l build/CI20*/latest/u-boot-spl.bin 
-rwxr-xr-x  1 hns  staff  13320 23 Mai 13:43 build/CI20-new/latest/u-boot-spl.bin
-rwxr-xr-x  1 hns  staff  13320 23 Mai 09:48 build/CI20/latest/u-boot-spl.bin
iMac:U-Boot hns$ 

The old code has a baked in version identification: 2013.07-00032-ga0be72af44d-dirty 
while the new one says 2013.07-00034-g8f4c0881a8f

So they are indeed almost the same base version which could make a git diff useful
and not overloaded with unrelated stuff...

BR,
Nikolaus

> Am 23.05.2025 um 13:51 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi,
> 
> I have spent some minutes to look at what we need to
> boot the mips-generic kernel on the CI20.
> 
> Of course we initially need to enable U-Boot to load the FDT
> from µSD and modify the memory size etc.
> 
> For the CI20 U-Boot we have two options:
> 
> a) modify the CI20 U-Boot that is working to add (optional)
> FDT loading. It is a special CI20 only U-Boot 2013.10:
> 
> https://git.goldelico.com/?p=letux-uboot.git;a=shortlog;h=refs/heads/ci20-v2013.10
> 
> The binaries we usually install through makesd are here:
> 
> https://download.goldelico.com/letux-u-boot/CI20/latest/
> 
> A drawback of this approach is that the U-Boot.img itself is
> not stored in a first partition of the µSD, rather at a fixed
> location the SPL knows about. This makes modifying/improving the
> U-Boot more difficult.
> 
> b) configure the x1600/x2000 U-Boot 2013.07 which already has the
> FDT additions in code for the CI20 and uses a dual-partition scheme.
> 
> https://git.goldelico.com/?p=letux-uboot.git;a=shortlog;h=refs/heads/ingenic-x1600-v4
> 
> There we find a a config option and include/configs/ci20.h.
> 
> I had to tweak the latter a little to get it compiled (patches included
> above). There are some tools to add a LOGO bitmap as ELF-Linux binaries
> only in the source tree and they failed to recompile from source. And I
> had to change the CONFIG_SYS_UART_INDEX to 4.
> 
> But I only get this from SPL on the 115200 bps console...
> 
> b$@ᇤ夆ąFĤĄ䥧bb$@ᇤ夆̅FĬĄ䥧bʅdeĄB
> 
> Binaries: https://download.goldelico.com/letux-u-boot/CI20-new/latest/
> 
> Some preliminary conclusions:
> - it is indeed possible to compile some CI20 SPL that is doing something after boot from µSD
> - the CI20 support in 2013.07 may have never been tested and has bugs
> - or I have to adjust some more configs
> - or some x1600/x2000 patches in this tree have damaged the CI20 setup (CGU?)
> 
> Generally I tend to go path b) and debug because then we have a single
> U-Boot tree for all Ingenic/Lumissil devices.
> 
> What do you think?
> 
> BR,
> Nikolaus
> 
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