Hello,

There are no technical reason why BL2 is not supported. There are internal discussions to add it but not yet validated and won't be available quickly.

Ronan,

[Shape, rectangle Description automatically generated]

Ronan GABOU | Tel: +33 1 58 07 80 19 MDG / General Purpose Microcontroller Sub-Group / Wireless Business Line / Cellular

[cid:image002.png@01DCF4F7.48AC40A0]https://www.facebook.com/STMicroelectronics.NV/ [cid:image003.png@01DCF4F7.48AC40A0] https://twitter.com/st_world [cid:image004.png@01DCF4F7.48AC40A0] https://www.linkedin.com/company/stmicroelectronics/ [cid:image005.png@01DCF4F7.48AC40A0] https://www.instagram.com/stmicroelectronics.nv/ [cid:image006.png@01DCF4F7.48AC40A0] https://www.youtube.com/user/STonlineMedia ST online: www.st.com online: www.st.com

From: Jaun, Mario via TF-M tf-m@lists.trustedfirmware.org Sent: Friday, June 5, 2026 11:38 AM To: tf-m@lists.trustedfirmware.org Subject: [TF-M] BL2 support for STM32U3 platform

Hello

We are interested in integrating TF-M into a project which is based on a STM32U3 MCU. The documentation states under limitations "TF-M Supported without BL1/BL2". Are there technical reasons that BL2 is not supported? If no, is support planned to be implemented in the near future? If no, would you be open for contributions regarding adding BL2 support?

Thanks for your response.

Best Mario