variants: allow mbedtls buffer lazy allocation#512
Merged
Conversation
Built
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| Artifact | Board | Core | Tests | RAM | Sketches | Warnings | Errors |
|---|---|---|---|---|---|---|---|
✅* zephyr_contrib |
ek_ra8d1
| 📗 | ✅* |
11.9% |
2 | 2 | - |
frdm_mcxn947
| 7 🏷️ | ✅* |
58.0% |
2 | 2 | - | |
frdm_rw612
| 2 🏷️ | ✅* |
83.0% |
2 | 2 | - | |
✔️* zephyr_main |
giga
| 5 🏷️ | ✅* |
39.4% |
58 | 16 | - |
nano33ble
| 1 🏷️ | ✅* |
78.8% |
30 | 8 | - | |
nano_matter
| 1 🏷️ | ✅* |
|
22 | 8 | - | |
nicla_sense
| 2 🏷️ | ✅* |
|
18 | 8 | - | |
nicla_vision
| 5 🏷️ | ✔️* |
41.7% |
52 | 16 | (2*) | |
opta
| 5 🏷️ | ✅* |
42.4% |
62 | 18 | - | |
portentac33
| 3 🏷️ | ✅* |
80.6% |
66 | 16 | - | |
portentah7
| 4 🏷️ | ✅* |
43.2% |
74 | 16 | - | |
✅* zephyr_unoq |
unoq
| 📗 | ✅* |
26.9% |
56 | 8 | - |
Legend
Board Test Status description 🔥 🔥 Test run failed to complete. ❌ 🔴 Test completed with unexpected errors. ⁉️ ⁉️ Test was expected to fail but passed; exception entry is outdated. ✔️* 🚫 Test completed with errors, but all are known/expected. ✅* 🟡 Test completed with some warnings; no errors detected. ✅ 🟢 Test passed successfully, with no warnings or errors. 🌑 🌑 Test was skipped.
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Pull request overview
This PR reduces baseline RAM usage on selected variants by preventing Zephyr/mbedTLS from reserving its heap buffer at boot, and instead initializing the mbedTLS buffer allocator only when TLS-capable sketch code is linked/used.
Changes:
- Disable automatic mbedTLS initialization (
CONFIG_MBEDTLS_INIT=n) in multiple STM32H747 / Portenta C33 variants to avoid reserving the mbedTLS heap by default. - Add a
ZephyrSSLClientimplementation that initializes the mbedTLS memory buffer allocator from a sketch-side static heap when TLS is used. - Export
mbedtls_memory_buffer_alloc_initfrom the loader to support sketch-side initialization, and adjust SocketWrapper headers’ include structure.
Reviewed changes
Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.conf | Disable automatic mbedTLS init on Portenta H7 variant to avoid reserving heap at boot |
| variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.conf | Disable automatic mbedTLS init on Portenta C33 variant |
| variants/arduino_opta_stm32h747xx_m7/arduino_opta_stm32h747xx_m7.conf | Disable automatic mbedTLS init on Opta variant |
| variants/arduino_nicla_vision_stm32h747xx_m7/arduino_nicla_vision_stm32h747xx_m7.conf | Disable automatic mbedTLS init on Nicla Vision variant |
| variants/arduino_giga_r1_stm32h747xx_m7/arduino_giga_r1_stm32h747xx_m7.conf | Disable automatic mbedTLS init on GIGA R1 variant |
| loader/llext_exports.c | Export mbedTLS buffer allocator init symbol for sketch-side TLS initialization |
| libraries/SocketWrapper/ZephyrUDP.h | Remove direct Arduino.h include (now provided by SocketWrapper.h) |
| libraries/SocketWrapper/ZephyrSSLClient.h | Add ZephyrSSLClient wrapper that gates TLS connect on mbedTLS readiness |
| libraries/SocketWrapper/ZephyrSSLClient.cpp | Implement sketch-side mbedTLS buffer allocator initialization |
| libraries/SocketWrapper/SocketWrapper.h | Centralize Arduino.h include for SocketWrapper consumers |
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facchinm
previously approved these changes
Jun 15, 2026
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Built
|
| Artifact | Board | Core | Tests | RAM | Sketches | Warnings | Errors |
|---|---|---|---|---|---|---|---|
✅* zephyr_contrib |
ek_ra8d1
| 📗 | ✅* |
11.9% |
2 | 2 | - |
frdm_mcxn947
| 7 🏷️ | ✅* |
58.0% |
2 | 2 | - | |
frdm_rw612
| 2 🏷️ | ✅* |
83.0% |
2 | 2 | - | |
✔️* zephyr_main |
giga
| 5 🏷️ | ✅* |
39.4% |
58 | 16 | - |
nano33ble
| 1 🏷️ | ✅* |
78.8% |
30 | 8 | - | |
nano_matter
| 1 🏷️ | ✅* |
|
22 | 8 | - | |
nicla_sense
| 2 🏷️ | ✅* |
|
18 | 8 | - | |
nicla_vision
| 5 🏷️ | ✔️* |
41.7% |
52 | 16 | (2*) | |
opta
| 5 🏷️ | ✅* |
42.4% |
62 | 18 | - | |
portentac33
| 3 🏷️ | ✅* |
80.6% |
66 | 16 | - | |
portentah7
| 4 🏷️ | ✅* |
43.2% |
74 | 16 | - | |
✅* zephyr_unoq |
unoq
| 📗 | ✅* |
43.5% |
56 | 8 | - |
Legend
Board Test Status description 🔥 🔥 Test run failed to complete. ❌ 🔴 Test completed with unexpected errors. ⁉️ ⁉️ Test was expected to fail but passed; exception entry is outdated. ✔️* 🚫 Test completed with errors, but all are known/expected. ✅* 🟡 Test completed with some warnings; no errors detected. ✅ 🟢 Test passed successfully, with no warnings or errors. 🌑 🌑 Test was skipped.
Author
|
Tested on GIGA OPTA and PORTENTA C33 |
Moving mbedtls init function from the loader to the core allow lazy allocation of mbedtls buffer
Built
|
| Artifact | Board | Core | Tests | RAM | Sketches | Warnings | Errors |
|---|---|---|---|---|---|---|---|
✅* zephyr_contrib |
ek_ra8d1
| 📗 | ✅* |
11.9% |
2 | 2 | - |
frdm_mcxn947
| 7 🏷️ | ✅* |
58.0% |
2 | 2 | - | |
frdm_rw612
| 2 🏷️ | ✅* |
83.0% |
2 | 2 | - | |
✔️* zephyr_main |
giga
| 5 🏷️ | ✅* |
39.4% |
58 | 16 | - |
nano33ble
| 1 🏷️ | ✅* |
78.8% |
30 | 8 | - | |
nano_matter
| 1 🏷️ | ✅* |
|
22 | 8 | - | |
nicla_sense
| 2 🏷️ | ✅* |
|
18 | 8 | - | |
nicla_vision
| 5 🏷️ | ✔️* |
41.7% |
52 | 16 | (2*) | |
opta
| 5 🏷️ | ✅* |
42.4% |
62 | 18 | - | |
portentac33
| 3 🏷️ | ✅* |
80.6% |
66 | 16 | - | |
portentah7
| 4 🏷️ | ✅* |
43.2% |
74 | 16 | - | |
✅* zephyr_unoq |
unoq
| 📗 | ✅* |
43.5% |
56 | 8 | - |
Legend
Board Test Status description 🔥 🔥 Test run failed to complete. ❌ 🔴 Test completed with unexpected errors. ⁉️ ⁉️ Test was expected to fail but passed; exception entry is outdated. ✔️* 🚫 Test completed with errors, but all are known/expected. ✅* 🟡 Test completed with some warnings; no errors detected. ✅ 🟢 Test passed successfully, with no warnings or errors. 🌑 🌑 Test was skipped.
|
Memory usage change @ 1467ed7
Click for full report table
Click for full report CSV |
pillo79
approved these changes
Jun 16, 2026
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starting from this discussion This PR is an alternative implementation trying to reduce mbedtls RAM usage allocating the buffer only if the sketch includes TLS functionality.
Test results on GIGA R1
WiFiWebClient.ino sketchWiFiWebClientTLS.ino