What really happens on Pyra bootup?


Hhhendrik

Still Fresh
Joined
Jun 7, 2025
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Hi fellow Pyramanics,

I have the crazy idea to address some of the remaining ailments of the Pyra, (e.g. USB support in u-boot (for netboot), strange noise in headphones etc.).
For that, I would need to quickly try out kernels, u-boot images etc. -- which also explains my interest in netboot.
So far, I have failed to boot a custom MLO/u-boot image.

So my question to the hardware/firmware experts: How does Pyra actually start up? AFAIK, it looks for the MLO, which starts u-boot, and then ... what flashes the LEDs on the powerbutton / logo to flash? Which code looks at the partitions/boot flag of the left SD slot and decides if and what to boot? Are there "magic keys" I need to press?

A lot of information found here in the forum or the Pandorawiki is for Pandora, and it did not work for me.
I tried creating a disk with the Letuxos "makesd" tool, put it in the left SD slot, in the internal µSD slot, it always seems to boot from the internal u-boot/MLO.
 
It's been ages since I've dealt with anything custom on the Pyra, I've been spoiled with pre-built images that just boot when inserted. So I don't believe there is a magic key, it just needs to be bootable. I remember the makeSD script being a bit half baked as well.
 
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