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Intel updates mysterious 'software-defined silicon' code in the Linux kernel

Yeah, right, Chipzilla: we totally believe your line this isn't a real plan, even though PCI supports it

Update Intel has updated the code it says allows the implementation of "software-defined silicon" (SDSi).

Chipzilla dropped some code for SDSi into the Linux Kernel in September 2021, describing it as tech that allows users to activate dormant features in silicon. The code outlined a process for enabling new features by verifying cryptographically signed licences.

A new post to the Linux Kernel Mailing List from David E. Box, a Linux dev who works at Intel, explains version two of Intel's SDSi code.

Box explained the update offers “changes to the current intel_pmt driver to give it broader support for Intel defined PCIe VSEC and DVSEC features. It moves the implementation from MFD to the auxiliary bus and creates a generic framework for enumerating the extended capabilities. It also adds support for a new VSEC, Software Defined Silicon (SDSi).”

VSEC stands for “Vendor-Specific Extended Capability,” in case you are wondering. And this PCI-SIG Engineering Change Notice (PDF) from 2015 states it “allows PCI Express component vendors to use the Extended Capability mechanism to expose vendor-specific registers.”

The Register asked Intel about SDSi in the wake of Box's first posts on the matter. Intel declined to offer details of its plans, and even told The Register SDSi might not have anything to do with an actual product and/or might never be used.

We were sceptical of that assertion because making the effort to add code to the Linux kernel without planning for it to be used is thoroughly counter-intuitive. It's also the sort of thing that annoys key Linux maintainers: Greg Kroah-Hartman fumed when researchers conducted an experiment by trying to add insecure code to the kernel and then testily pointed out that 80 developers worked to clean up the resulting mess.

Intel knows better than to provoke that sort of ire. And now that it's bothered to refine its SDSi efforts, the non-explanation for its kernel contributions is even flimsier than before.

We've therefore asked Intel to again explain its SDSi ambitions. If we receive a meaningful response, we'll let you know. ®

Updated 23:15 UTC, 8 December

"Intel has advised they have nothing further to add at this point," reads a statement sent to The Register.

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