We had reports of multiple Linux servers (Dell, HPE) hanging or crashing on boot after updating the Intel microcode package to version 20260512. All affected servers are based on Intel Xeon 6756E processors (Sierra Forest family). Reverting to microcode package version 20260210 solves the problem.
Investigation revealed that the problem only happens if the system firmware and/or the initial microcode version is old (update from 0x03000392 or 0x03000393 to 0x030003a3 worked fine in our tests, while update from 0x03000362 to 0x030003a3 failed). We also found that updating the system firmware as a whole, solves the problem. So the microcode itself seems to be good, the problem is either an incompatibility with some other component of the system firmware, or an issue with updating the microcode while the kernel is already running.
In essence, this issue looks similar to issue #112 but for a different CPU family.
We had reports of multiple Linux servers (Dell, HPE) hanging or crashing on boot after updating the Intel microcode package to version 20260512. All affected servers are based on Intel Xeon 6756E processors (Sierra Forest family). Reverting to microcode package version 20260210 solves the problem.
Investigation revealed that the problem only happens if the system firmware and/or the initial microcode version is old (update from 0x03000392 or 0x03000393 to 0x030003a3 worked fine in our tests, while update from 0x03000362 to 0x030003a3 failed). We also found that updating the system firmware as a whole, solves the problem. So the microcode itself seems to be good, the problem is either an incompatibility with some other component of the system firmware, or an issue with updating the microcode while the kernel is already running.
In essence, this issue looks similar to issue #112 but for a different CPU family.