CMSIS Components used by mbed are now BSD Licensed

in ARM, open source by DP | 6 comments


Viswa writes, “ARM and has released the components of CMSIS software under a permissive BSD license. CMSIS is common layer provided by ARM for accessing the core registers of ARM Cortex-M processor which inside Cortex-M MCUs. All Cortex-M MCU vendor make use of this library for the software drivers. This was until now under a custom license not suitable to be combined with many Free Open Source licenses.”

This entry was posted in ARM, open source and tagged , .


  1. mossmann says:

    This is very welcome news, but they should cut that long explanatory paragraph if they don’t want to look like dicks. It sounds like they are claiming that this re-licensing is simply a clarification and that any prior confusion was the fault of open source developers. How about: “Sorry. We screwed up and tried to release open source code containing closed source components. We fixed it.”

  2. Paul says:

    This would be fantastic news, but I’m currently unable to locate advertised CMSIS package on the ARM downloads site. I’ve posted comment to the original article, please join me if you’re confused too.

  3. Paul says:

    So, yes, in the end it is available, though not without confusion and trickery, read whole story here:

    I’ve imported BSD components into git:

    • mossmann says:

      To me it looks even worse than you describe, Paul, but thanks for taking the time to pick out the BSD licensed bits. In the forum thread you link, Emilio specifically links: “We are distributing some of its components in the mbed SDK sources”. I clicked through and am finding non-BSD licensed code (example). It’s not stuff that is in your (Paul’s) repo.

      “This file can be freely distributed within development tools that are supporting such ARM based processors.” That’s not BSD and not open source.

      I would love to be proven wrong, but this looks like the second time mbed has made a BS announcement about being open source. Worse, DP has posted both announcements with a prominent OSI logo without verifying the claims. DP, you are part of the problem.

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