Temperature-based runtime variability in victim address selection for probabilistic schemes for row hammer

Abstract

A probabilistic scheme that uses temperature to reload an LFSR at runtime introduces randomness to prevent row hammer attacks. In one example, a memory controller includes input/output (I/O) interface circuitry to receive memory access requests from a processor. A linear feedback shift register (LFSR) in the memory controller is shifted in response to receipt of a memory access request to a target address. The shift register is compared a value in the LFSR with a pre-determined value. If the value in the LFSR is equal to the predetermined value, a refresh is triggered to one or more neighboring addresses of the target address. The LFSR is reloaded with one of multiple seeds based on a temperature (for example, from an on-die thermal sensor, a DIMM sensor, and/or other temperature). Selecting one of multiple seeds based on temperature on the fly makes the scheme unpredictable and robust against row hammer.