Nest (NX) Accelerator Coprocessor ================================= The NX coprocessor is present in P7+ or later processors. Each NX node represents a unique NX coprocessor. The nodes are located under an xscom node, as: :: /xscom@/nx@ With unique xscom and nx addresses. Their compatible node contains "ibm,power-nx". NX 842 Coprocessor ------------------ This is the memory compression coprocessor, which uses the IBM proprietary 842 compression algorithm and format. Each nx node contains an 842 engine. :: ibm,842-coprocessor-type : CT value common to all 842 coprocessors ibm,842-coprocessor-instance : CI value unique to all 842 coprocessors Access to the coprocessor requires using the ICSWX instruction, which uses a specific format including a Coprocessor Type (CT) and Coprocessor Instance (CI) value to address each request to the right coprocessor. The driver should use the CT and CI values for a particular node to communicate with it. For all 842 coprocessors in the system, the CT value will (should) be the same, while each will have a different CI value. The driver can use CI 0 to allow the hardware to automatically select which coprocessor instance to use. NX RNG Coprocessor ------------------ This is the Random Number Generator (RNG) coprocessor, which is a part of each NX coprocessor. Each node represents a unique RNG coprocessor. Its nodes are not under the main nx node, they are located at: :: /hwrng@ : RNG at address ibm,chip-id : chip id where the RNG is reg : address of the register to read from Each read from the RNG register will provide a new random number.