Bootloader option to load from SD?

[u77345]

I'd like to add an option to the example 38 bootloader, that boots an image from the microsd instead of attempting the network loading, if a GPIO is pulled low. Otherwise, it loads from the network. Is there any concern doing so, or perhaps an example loading the kernel from the filesystem?

[rsta2]

I think this should work and can be implemented as an additional task in sample/38-bootloader. I do not have an example by hand, but would prepare one, if you need help. I would need to know, on which RPi model it will run, so that I can test it on the right model.

[u77345]

The target board is "Raspberry Pi Model B R2". Thanks for offering support!

[rsta2]

You find the source code of the extended bootloader appended. Configuration is in kernel.h and kernel.cpp. By default the button must be connected from GPIO18 (SoC number) to GND. The kernel image to be loaded is mykernel.img in the root directory of the SD card. You can define NO_NET_BOOT to disable the booting functions from network.

bootloader-extended.zip

[u77345]

Thanks Rene, all 3 boot modes worked beautifully.

[rsta2]

I'm glad, that it helped.