havaker

The license choice is explained with the following:

> [...] we accommodate the business need for proprietary kernel modules. Unlike GPL, the MPL permits the linking of MPL-covered files with proprietary code.

Glancing at the readme, it also looks like they are treating it as a big feature:

> Asterinas surpasses Linux in terms of developer friendliness. It empowers kernel developers to [...] choose between releasing their kernel modules as open source or keeping them proprietary, thanks to the flexibility offered by MPL.

Can't wait to glue some proprietary blobs to this new, secure rust kernel /s

Open source usually means that you are able to modify and redistribute the software in question freely. However between open and closed, there is another class - source-available software. From its wikipedia page:

> Any software is source-available in the broad sense as long its source code is distributed along with it, even if the user has no legal rights to use, share, modify or even compile it.