1# SPDX-License-Identifier: GPL-2.0-only 2menuconfig CXL_BUS 3 tristate "CXL (Compute Express Link) Devices Support" 4 depends on PCI 5 help 6 CXL is a bus that is electrically compatible with PCI Express, but 7 layers three protocols on that signalling (CXL.io, CXL.cache, and 8 CXL.mem). The CXL.cache protocol allows devices to hold cachelines 9 locally, the CXL.mem protocol allows devices to be fully coherent 10 memory targets, the CXL.io protocol is equivalent to PCI Express. 11 Say 'y' to enable support for the configuration and management of 12 devices supporting these protocols. 13 14if CXL_BUS 15 16config CXL_MEM 17 tristate "CXL.mem: Memory Devices" 18 help 19 The CXL.mem protocol allows a device to act as a provider of 20 "System RAM" and/or "Persistent Memory" that is fully coherent 21 as if the memory was attached to the typical CPU memory 22 controller. 23 24 Say 'y/m' to enable a driver (named "cxl_mem.ko" when built as 25 a module) that will attach to CXL.mem devices for 26 configuration, provisioning, and health monitoring. This 27 driver is required for dynamic provisioning of CXL.mem 28 attached memory which is a prerequisite for persistent memory 29 support. Typically volatile memory is mapped by platform 30 firmware and included in the platform memory map, but in some 31 cases the OS is responsible for mapping that memory. See 32 Chapter 2.3 Type 3 CXL Device in the CXL 2.0 specification. 33 34 If unsure say 'm'. 35 36config CXL_MEM_RAW_COMMANDS 37 bool "RAW Command Interface for Memory Devices" 38 depends on CXL_MEM 39 help 40 Enable CXL RAW command interface. 41 42 The CXL driver ioctl interface may assign a kernel ioctl command 43 number for each specification defined opcode. At any given point in 44 time the number of opcodes that the specification defines and a device 45 may implement may exceed the kernel's set of associated ioctl function 46 numbers. The mismatch is either by omission, specification is too new, 47 or by design. When prototyping new hardware, or developing / debugging 48 the driver it is useful to be able to submit any possible command to 49 the hardware, even commands that may crash the kernel due to their 50 potential impact to memory currently in use by the kernel. 51 52 If developing CXL hardware or the driver say Y, otherwise say N. 53endif 54