With the vast majority of x86/x86_64 systems supporting restarting the system using ACPi, BIOS, or even the KBD keyboard controller, with Linux 7.1 is now support in place for using custom restart handlers registered by drivers, such as in place for other CPU architectures.

This change to the Linux x86 restart behavior to better align it with other architectures comes due to the restart behavior of the Lightning Mountain SoC from Intel / Max Linear . Lightning Mountain isn't following conventional x86/x86_54 restart methods but depends upon a custom restart handler provided by its RCU driver (reset-intwl-gw) to trigger a global reset signal.

But until now the common Linux x86/x86_64 kernel code isn't actually calling do_kernel_restart() like on other architectures for triggering the custom restart handlers.

So with a small change merged for Linux 7.1, it's now being called for quirky x86/x86_64 hardware going about custom restart methods and aligned with the behavior of other non-x86 architectures on Linux. And in turn Lightning Mountain can properly restart under Linux.

"Ensure that drivers which register custom restart handlers (such as those needed for SoC-based x86 devices like Intel Lightning Mountain) are actually invoked during reboot, bringing x86 in line with how other architectures handle this."

This tid-bit was merged as part of the x86/misc changes for Linux 7.1.