on the Ubuntu server you should be able to clone this https://github.com/giuliomoro/Bootloader-Builder/ .
You can then edit the file
patches/bela/0003-Allow-to-override-the-CPU-speed-at-compile-time.patch so that lines 19 looks like this:
+#define OVERRIDE_CPU_SPEED MPUPLL_M_300
you can replace
Then you can build the bootloader with
./build.sh. If everything goes fine, this will create two files:
If the above is too complicated for you, I can give you a pre-built binary, but then you would not be able to customize the speed of the CPU.
u-boot.img files built above can then be copied to the
BELABOOT partition on the board, however you need to ensure that they are copied at the very beginning of the partition, so follow the instructions below.
- insert the SD card on your macbook, it should show up at
- copy MLO and u-boot.img from the server to the folder containing the script below
- run the script (untested)
<< script removed to avoid confusion, see updated version below>>
- remove the SD card and put it into Bela and start it. Once you can log in (it may take over a minute now), do
cat /proc/cpuinfo and hopefully you will see there the "BogoMIPS" value to be around the frequency you set.