Secondary CPU MMU initialization using page fault exception

摘要

In a computer system with multiple central processing units (CPUs), initialization of a memory management unit (MMU) for a secondary CPU is performed using an exception generated by the MMU. In general, this technique leverages the exception handling features of the secondary CPU to switch the CPU from executing secondary CPU initialization code with the MMU “off” to executing secondary CPU initialization code with the MMU “on.” Advantageously, in contrast to conventional techniques for MMU initialization, this exception-based technique does not require identity mapping of the secondary CPU initialization code to ensure proper execution of the secondary CPU initialization code.

主权项

1. A method of initializing a memory management unit (MMU) to perform virtual address to physical address memory mapping for a secondary central processing unit (CPU) in a multiple CPU system, comprising:
executing an activation instruction to cause the memory management unit to perform address mapping based on page tables; attempting to fetch an instruction at a first virtual address sequentially following an address of the activation instruction and triggering an exception because the first virtual address does not have a mapping to a physical address in the page tables; and responsive to the exception, fetching an instruction at a second virtual address that has a mapping to a physical address in the page tables, and executing the instruction at the second virtual address, wherein the physical address to which the second virtual address is mapped corresponds to a physical address of an instruction to initialize the secondary CPU.