zephyr: use feature levels for minimal and standard build configurations #17680
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bikeNomad
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Jul 15, 2025
…ython#17680. @dpgeorge's PR micropython#17680 defines the standard Zephyr config based on MICROPY_CONFIG_ROM_LEVEL_BASIC. This allows for simplifying the XIAO BLE board's mpconfigport-xiao.h. Signed-off-by: Ned Konz <ned@metamagix.tech>
This commit adjusts the configuration of the minimal zephyr build to use
MICROPY_CONFIG_ROM_LEVEL_MINIMUM. That's a lot cleaner than explicitly
enabling/disabling options.
Prior to this change the minimal build for qemu_cortex_m3 had size:
Memory region Used Size Region Size %age Used
FLASH: 114436 B 256 KB 43.65%
RAM: 26320 B 64 KB 40.16%
and had the following test results (running using the CI settings, ie
`-d basics float --exclude inf_nan_arith`):
352 tests performed (7092 individual testcases)
352 tests passed
254 tests skipped: ...
With the changes here the qemu_cortex_m3 size is now:
Memory region Used Size Region Size %age Used
FLASH: 99428 B 256 KB 37.93%
RAM: 26312 B 64 KB 40.15%
That's a good decrease of about 15k firmware size. And the test suite
still passes with:
342 tests performed (6776 individual testcases)
341 tests passed
265 tests skipped: ...
Signed-off-by: Damien George <damien@micropython.org>
This commit adjusts the configuration of the standard zephyr build to use
MICROPY_CONFIG_ROM_LEVEL_BASIC_FEATURES. That's a lot cleaner than
explicitly enabling/disabling options, and allows boards to more easily
fine-tune the settings, eg select a different feature level.
Features that are now enabled are:
- async/await keyword support
- `filter`, `property` and `reversed` builtins
- `range` attributes
- `str.count()` method
- `array` module with `array.array` object
- `collections` module with `collections.namedtuple` object
- `struct` module with everything
- `id = const()` and constant folding in the compiler
Bulding qemu_cortex_m3, the code size was originally:
Memory region Used Size Region Size %age Used
FLASH: 193864 B 256 KB 73.95%
RAM: 61992 B 64 KB 94.59%
and with this commit it is now:
Memory region Used Size Region Size %age Used
FLASH: 200698 B 256 KB 76.56%
RAM: 61992 B 64 KB 94.59%
That's a mild increase of +6834 bytes flash usage for a good selection of
new features.
Signed-off-by: Damien George <damien@micropython.org>
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Summary
There are two commits here, both simplifying the zephyr configuration to use ROM feature level settings.
The minimal configuration now uses MICROPY_CONFIG_ROM_LEVEL_MINIMUM. This decreases firmware size by about 15k, and the tests still pass.
The standard configuration now uses MICROPY_CONFIG_ROM_LEVEL_BASIC_FEATURES. This increases firmware size by about 6.5k, but adds some useful things:
filter,propertyandreversedbuiltinsrangeattributesstr.count()methodarraymodule witharray.arrayobjectcollectionsmodule withcollections.namedtupleobjectstructmodule with everythingid = const()and constant folding in the compiler__all__support in modulesUsing feature levels simplifies the configurations and allows boards to better fine-tune their config, eg #17679 should be much simpler with this PR.
Testing
Tested locally with qemu_cortex_m3 build, both minimal and standard. Tested also with frdm_k64f and the standard configuration.
Will also be tested by CI.
Trade-offs and Alternatives
This should be a win all round. After all, this is what the feature levels are for (and zephyr so far didn't convert to use them, that's what's done here).