Memory channel that supports near memory and far memory access
View Patent ↗A semiconductor chip comprising memory controller circuitry having interface circuitry to couple to a memory channel. The memory controller includes first logic circuitry to implement a first memory channel protocol on the memory channel. The first memory channel protocol is specific to a first volatile system memory technology. The interface also includes second logic circuitry to implement a second memory channel protocol on the memory channel. The second memory channel protocol is specific to a second non volatile system memory technology. The second memory channel protocol is a transactional protocol.
1. A dual-in line memory module (DIMM), comprising:
a) an interface to couple to a memory controller over an industry standard dual data rate memory channel having a first protocol that includes deterministic memory access timing;
b) non volatile memory, the non volatile memory having non deterministic memory access timing;
c) DRAM memory to act as a cache for the non volatile memory;
d) on board electronic circuitry to:
i) determine hits in the cache and determine misses in the cache;
ii) identify errors in data read from the non volatile memory;
iii) queue read and write requests that are to be serviced from the non volatile memory to enable the DIMM to respond to the read and write requests over the industry standard dual data rate memory channel out-of-order as a consequence of the non deterministic access timing of the non volatile memory;
iv) support a second protocol over the industry standard dual data rate memory channel, the second protocol to enable the out-of-order response behavior of the DIMM, the second protocol including handling of read requests by passing of a transaction identifier between the DIMM and the memory controller, the second protocol including handling of write requests by passing state information of the DIMM's pending write requests between the DIMM and the memory controller.
2. The dual in-line memory module of claim 1 where the non volatile memory is comprised of flash memory.
3. The dual in-line memory module of claim 1 where the non volatile memory is comprised of three-dimensional stacked memory storage cells.
4. The dual in-line memory module of claim 1 wherein the non volatile memory is to be allocated system memory address space.