Detecting memory mismatch between lockstep systems using a memory signature

A method comprising:

• receiving, at a first memory controller of a first computer system including a first memory and a first central processing unit (CPU) and the first memory controller, a request to perform a first write operation by the first memory controller to the first memory, the first write operation to store data at an address in the first memory;
• generating, by a first signature generator of the first computer system, a first digital signature representing the first write operation;
• storing, by the first signature generator, the first digital signature in a first signature register of the first CPU;
• receiving, at a second memory controller of a second computer system including a second memory and a second CPU and the second memory controller, a request to perform a second write operation by the second memory controller to the second memory, the second write operation to store the data at the address in the second memory, the second computer system operating in lockstep with the first computer system;
• generating, by a second signature generator of the second computer system, a second digital signature representing the second write operation;
• storing, by the second signature generator, the second digital signature in a second signature register of the second CPU;
• and
• comparing the first digital signature to the second digital signature and detecting a lockstep error when the first digital signature does not match the second digital signature.

At least one non-transitory machine-readable medium comprising a plurality of instructions that in response to being executed by a processor in a computer system cause the computer system to:

• receive, at a memory controller of the computer system including a memory and a CPU and the memory controller, a request to perform a write operation by the memory controller to the memory, the write operation to store the data at an address in the memory, the computer system operating in lockstep with a second computer system;
• generate, by a signature generator of the computer system, a digital signature representing the write operation;
• store, by the signature generator, the digital signature in a signature register of the CPU;
• receive a second digital signature representing a second write operation by a second memory controller to a second memory in the second computer system;
• and
• compare the digital signature to the second digital signature and detect a lockstep error when the digital signature does not match the second digital signature.