System and method for selectively enabling load-on-write of dynamic ROM data to RAM

摘要

A system and method for loading dynamic data stored in read-only memory (ROM) is loaded into random access memory (RAM) only when it is being modified. Unmodified dynamic data is used from ROM saving valuable RAM space. Virtual memory page table entries are created for all dynamic data with the physical reference pointing to the dynamic data in ROM. Page table entries in a translation table for dynamic data in ROM include a virtual address to physical address mapping and are marked read-only causing a write-access exception if an attempt is made to write to or update the dynamic data. Write-access exceptions are intercepted, and a write-access exception caused by an attempt to write to dynamic data in ROM causes the system to allocate a dynamic data page in RAM, copy the ROM data to the RAM, update the page table entry to point to the RAM page rather than the ROM page, and finally to update the dynamic data now present in read-write RAM.