In context: A patch was discovered this week that indicates Intel is preparing a new feature that can lock features of silicon behind software-based activation. It doesn't seem to be rolling out to the majority of Intel hardware mainstream consumers use right now, however.
The patch notes refer to the new feature as "Intel Software Defined Silicon" (SDSi). It should allow for additional features of a piece of silicon to be enabled after it has already been manufactured. It's entirely software-based, working through the activation of a license that the user might purchase. Additional documentation, including information about its operating system interface, is available on GitHub.
The patch notes don't mention what specific features SDSi may add. However, it is currently limited to Linux systems. According to Phoronix, which discovered the patch, Intel only intends to implement SDSi in its Xeon processors for now.
Phoronix compares this to a feature Intel tried to introduce to its Core processors around 2010 called Intel Upgrade Service. However, that didn't last long and never made it to Linux. Tom's Hardware compares the new feature to the more recent Intel Virtual RAID on CPU (VROC), which uses an Intel CPU's Volume Management Device (VMD) and is activated with a hardware-based key.
SDSi could be an effort by Intel to sell processors more cheaply by withholding features some users don't need. Then, if users find they do need the extras, they might pay for a software license to get them without having to buy a whole new processor.