Intel Granite Rapids Brings New "SBAF" Core Testing Capability
The past two years Intel Linux engineers have been developing the In-Field Scan (IFS) driver that since Xeon "Sapphire Rapids" processors has supported a means of help verifying the CPU's health and spotting any silicon defects either prior to commissioning new servers or reaffirming the silicon's health after deployment in an ongoing basis. In-Field Scan is especially valuable for hyperscalers, cloud providers, and others for verifying the health of CPUs via various functional tests that can be carried out on the processor internals at the choosing of the administrator.
With upcoming Intel Granite Rapids server processors, In-Field Scan is being extended to include Structural Based Functional Test at Field (SBAF) testing. Intel Linux engineer Kuppuswamy Sathyanarayanan posted a new set of patches overnight for extending the IFS Linux kernel driver for supporting this SBAF capability. The new patch series confirms SBAF with Granite Rapids and explains:
"This patch series adds support for Structural Based Functional Test at Field (SBAF) in the IFS driver. SBAF is a new type of testing that provides comprehensive core test coverage, complementing existing IFS tests like Scan at Field (SAF) and ArrayBist. Granite Rapids (GNR) is the first platform that supports SBAF.
SBAF mimics the manufacturing screening environment and leverages the same test suite. It makes use of Design For Test (DFT) observation sites and features to maximize coverage in minimum time.
Similar to the SAF test, SBAF isolates the core under test from the rest of the system during execution. Upon completion, the core seamlessly resets to its pre-test state and resumes normal operation. Any machine checks or hangs encountered during the test are confined to the isolated core, preventing disruption to the overall system. Like SAF test, the SBAF test is also divided into multiple batches, and each batch test can take hundreds of milliseconds (100-200 ms) to complete. If such a lengthy interruption is undesirable, it is recommended to relocate the time-sensitive applications to other cores for the duration of the test."
There's still time that we may see these new IFS driver additions ready for mainlining in time for the Linux v6.11 kernel cycle if all goes well.
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