Apparatus and method for synchronizing multiple accesses to common resources

摘要

A method and apparatus for providing a synchronization mechanism to control accesses to a non-cached shared resource by devices connected by a high speed interconnect is herein described. A semaphore is used to control access to a shared resource which is implemented by a pair of semaphore registers. A previous semaphore register is used to store the previous owner of the semaphore and a current semaphore register is used to either store the current owner of the semaphore or indicate that the semaphore is available. The current semaphore register is updated when the semaphore is available and is being taken or when the semaphore is being freed. The previous semaphore register is updated when the semaphore is freed.