1# SPDX-License-Identifier: GPL-2.0-only 2menuconfig CXL_BUS 3 tristate "CXL (Compute Express Link) Devices Support" 4 depends on PCI 5 select PCI_DOE 6 help 7 CXL is a bus that is electrically compatible with PCI Express, but 8 layers three protocols on that signalling (CXL.io, CXL.cache, and 9 CXL.mem). The CXL.cache protocol allows devices to hold cachelines 10 locally, the CXL.mem protocol allows devices to be fully coherent 11 memory targets, the CXL.io protocol is equivalent to PCI Express. 12 Say 'y' to enable support for the configuration and management of 13 devices supporting these protocols. 14 15if CXL_BUS 16 17config CXL_PCI 18 tristate "PCI manageability" 19 default CXL_BUS 20 help 21 The CXL specification defines a "CXL memory device" sub-class in the 22 PCI "memory controller" base class of devices. Device's identified by 23 this class code provide support for volatile and / or persistent 24 memory to be mapped into the system address map (Host-managed Device 25 Memory (HDM)). 26 27 Say 'y/m' to enable a driver that will attach to CXL memory expander 28 devices enumerated by the memory device class code for configuration 29 and management primarily via the mailbox interface. See Chapter 2.3 30 Type 3 CXL Device in the CXL 2.0 specification for more details. 31 32 If unsure say 'm'. 33 34config CXL_MEM_RAW_COMMANDS 35 bool "RAW Command Interface for Memory Devices" 36 depends on CXL_PCI 37 help 38 Enable CXL RAW command interface. 39 40 The CXL driver ioctl interface may assign a kernel ioctl command 41 number for each specification defined opcode. At any given point in 42 time the number of opcodes that the specification defines and a device 43 may implement may exceed the kernel's set of associated ioctl function 44 numbers. The mismatch is either by omission, specification is too new, 45 or by design. When prototyping new hardware, or developing / debugging 46 the driver it is useful to be able to submit any possible command to 47 the hardware, even commands that may crash the kernel due to their 48 potential impact to memory currently in use by the kernel. 49 50 If developing CXL hardware or the driver say Y, otherwise say N. 51 52config CXL_ACPI 53 tristate "CXL ACPI: Platform Support" 54 depends on ACPI 55 default CXL_BUS 56 select ACPI_TABLE_LIB 57 help 58 Enable support for host managed device memory (HDM) resources 59 published by a platform's ACPI CXL memory layout description. See 60 Chapter 9.14.1 CXL Early Discovery Table (CEDT) in the CXL 2.0 61 specification, and CXL Fixed Memory Window Structures (CEDT.CFMWS) 62 (https://www.computeexpresslink.org/spec-landing). The CXL core 63 consumes these resource to publish the root of a cxl_port decode 64 hierarchy to map regions that represent System RAM, or Persistent 65 Memory regions to be managed by LIBNVDIMM. 66 67 If unsure say 'm'. 68 69config CXL_PMEM 70 tristate "CXL PMEM: Persistent Memory Support" 71 depends on LIBNVDIMM 72 default CXL_BUS 73 help 74 In addition to typical memory resources a platform may also advertise 75 support for persistent memory attached via CXL. This support is 76 managed via a bridge driver from CXL to the LIBNVDIMM system 77 subsystem. Say 'y/m' to enable support for enumerating and 78 provisioning the persistent memory capacity of CXL memory expanders. 79 80 If unsure say 'm'. 81 82config CXL_MEM 83 tristate "CXL: Memory Expansion" 84 depends on CXL_PCI 85 default CXL_BUS 86 help 87 The CXL.mem protocol allows a device to act as a provider of "System 88 RAM" and/or "Persistent Memory" that is fully coherent as if the 89 memory were attached to the typical CPU memory controller. This is 90 known as HDM "Host-managed Device Memory". 91 92 Say 'y/m' to enable a driver that will attach to CXL.mem devices for 93 memory expansion and control of HDM. See Chapter 9.13 in the CXL 2.0 94 specification for a detailed description of HDM. 95 96 If unsure say 'm'. 97 98config CXL_PORT 99 default CXL_BUS 100 tristate 101 102config CXL_SUSPEND 103 def_bool y 104 depends on SUSPEND && CXL_MEM 105 106config CXL_REGION 107 bool "CXL: Region Support" 108 default CXL_BUS 109 # For MAX_PHYSMEM_BITS 110 depends on SPARSEMEM 111 select MEMREGION 112 select GET_FREE_REGION 113 help 114 Enable the CXL core to enumerate and provision CXL regions. A CXL 115 region is defined by one or more CXL expanders that decode a given 116 system-physical address range. For CXL regions established by 117 platform-firmware this option enables memory error handling to 118 identify the devices participating in a given interleaved memory 119 range. Otherwise, platform-firmware managed CXL is enabled by being 120 placed in the system address map and does not need a driver. 121 122 If unsure say 'y' 123 124config CXL_REGION_INVALIDATION_TEST 125 bool "CXL: Region Cache Management Bypass (TEST)" 126 depends on CXL_REGION 127 help 128 CXL Region management and security operations potentially invalidate 129 the content of CPU caches without notifying those caches to 130 invalidate the affected cachelines. The CXL Region driver attempts 131 to invalidate caches when those events occur. If that invalidation 132 fails the region will fail to enable. Reasons for cache 133 invalidation failure are due to the CPU not providing a cache 134 invalidation mechanism. For example usage of wbinvd is restricted to 135 bare metal x86. However, for testing purposes toggling this option 136 can disable that data integrity safety and proceed with enabling 137 regions when there might be conflicting contents in the CPU cache. 138 139 If unsure, or if this kernel is meant for production environments, 140 say N. 141 142endif 143