MicroPython Forum (Archive)

My interpretation of the documentation is that the boot file system (/flash or /sd) is where it first finds <boot.py> and <main.py>, starting the search with /sd if it exists, and that you can force /sd to be skipped and thus use /flash by either removing the SD card or putting an empty SKIPSD file on /flash, but that comes with the caveat that /sd will not be mounted if the SD card is present, but can be later mounted with os.mount.

So couldn't the same thing be done by simply renaming the <boot.py> file on /sd to something else? Would that force /flash to be the current directory so that the code on /flash would be used instead of code on /sd, while at the same time having /sd mounted and thus avoid having to use os.mount?

Looking at the source code: https://github.com/micropython/micropyt ... ain.c#L643

It either adds /sd and /sd/lib OR /flash and /flash/lib to sys.path. It will look for boot.py and main.py in the paths shown in sys.path.

smhodge wrote: ↑

Thu Sep 03, 2020 5:01 pm

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So couldn't the same thing be done by simply renaming the <boot.py> file on /sd to something else? Would that force /flash to be the current directory so that the code on /flash would be used instead of code on /sd, while at the same time having /sd mounted and thus avoid having to use os.mount?

I think SKIPSD is a security feature to prevent a hostile user fitting an SD card containing their own code.