| # SPDX-License-Identifier: GPL-2.0-only |
| menuconfig CXL_BUS |
| tristate "CXL (Compute Express Link) Devices Support" |
| depends on PCI |
| select PCI_DOE |
| help |
| CXL is a bus that is electrically compatible with PCI Express, but |
| layers three protocols on that signalling (CXL.io, CXL.cache, and |
| CXL.mem). The CXL.cache protocol allows devices to hold cachelines |
| locally, the CXL.mem protocol allows devices to be fully coherent |
| memory targets, the CXL.io protocol is equivalent to PCI Express. |
| Say 'y' to enable support for the configuration and management of |
| devices supporting these protocols. |
| |
| if CXL_BUS |
| |
| config CXL_PCI |
| tristate "PCI manageability" |
| default CXL_BUS |
| help |
| The CXL specification defines a "CXL memory device" sub-class in the |
| PCI "memory controller" base class of devices. Device's identified by |
| this class code provide support for volatile and / or persistent |
| memory to be mapped into the system address map (Host-managed Device |
| Memory (HDM)). |
| |
| Say 'y/m' to enable a driver that will attach to CXL memory expander |
| devices enumerated by the memory device class code for configuration |
| and management primarily via the mailbox interface. See Chapter 2.3 |
| Type 3 CXL Device in the CXL 2.0 specification for more details. |
| |
| If unsure say 'm'. |
| |
| config CXL_MEM_RAW_COMMANDS |
| bool "RAW Command Interface for Memory Devices" |
| depends on CXL_PCI |
| help |
| Enable CXL RAW command interface. |
| |
| The CXL driver ioctl interface may assign a kernel ioctl command |
| number for each specification defined opcode. At any given point in |
| time the number of opcodes that the specification defines and a device |
| may implement may exceed the kernel's set of associated ioctl function |
| numbers. The mismatch is either by omission, specification is too new, |
| or by design. When prototyping new hardware, or developing / debugging |
| the driver it is useful to be able to submit any possible command to |
| the hardware, even commands that may crash the kernel due to their |
| potential impact to memory currently in use by the kernel. |
| |
| If developing CXL hardware or the driver say Y, otherwise say N. |
| |
| config CXL_ACPI |
| tristate "CXL ACPI: Platform Support" |
| depends on ACPI |
| default CXL_BUS |
| select ACPI_TABLE_LIB |
| help |
| Enable support for host managed device memory (HDM) resources |
| published by a platform's ACPI CXL memory layout description. See |
| Chapter 9.14.1 CXL Early Discovery Table (CEDT) in the CXL 2.0 |
| specification, and CXL Fixed Memory Window Structures (CEDT.CFMWS) |
| (https://www.computeexpresslink.org/spec-landing). The CXL core |
| consumes these resource to publish the root of a cxl_port decode |
| hierarchy to map regions that represent System RAM, or Persistent |
| Memory regions to be managed by LIBNVDIMM. |
| |
| If unsure say 'm'. |
| |
| config CXL_PMEM |
| tristate "CXL PMEM: Persistent Memory Support" |
| depends on LIBNVDIMM |
| default CXL_BUS |
| help |
| In addition to typical memory resources a platform may also advertise |
| support for persistent memory attached via CXL. This support is |
| managed via a bridge driver from CXL to the LIBNVDIMM system |
| subsystem. Say 'y/m' to enable support for enumerating and |
| provisioning the persistent memory capacity of CXL memory expanders. |
| |
| If unsure say 'm'. |
| |
| config CXL_MEM |
| tristate "CXL: Memory Expansion" |
| depends on CXL_PCI |
| default CXL_BUS |
| help |
| The CXL.mem protocol allows a device to act as a provider of "System |
| RAM" and/or "Persistent Memory" that is fully coherent as if the |
| memory were attached to the typical CPU memory controller. This is |
| known as HDM "Host-managed Device Memory". |
| |
| Say 'y/m' to enable a driver that will attach to CXL.mem devices for |
| memory expansion and control of HDM. See Chapter 9.13 in the CXL 2.0 |
| specification for a detailed description of HDM. |
| |
| If unsure say 'm'. |
| |
| config CXL_PORT |
| default CXL_BUS |
| tristate |
| |
| config CXL_SUSPEND |
| def_bool y |
| depends on SUSPEND && CXL_MEM |
| |
| config CXL_REGION |
| bool "CXL: Region Support" |
| default CXL_BUS |
| # For MAX_PHYSMEM_BITS |
| depends on SPARSEMEM |
| select MEMREGION |
| select GET_FREE_REGION |
| help |
| Enable the CXL core to enumerate and provision CXL regions. A CXL |
| region is defined by one or more CXL expanders that decode a given |
| system-physical address range. For CXL regions established by |
| platform-firmware this option enables memory error handling to |
| identify the devices participating in a given interleaved memory |
| range. Otherwise, platform-firmware managed CXL is enabled by being |
| placed in the system address map and does not need a driver. |
| |
| If unsure say 'y' |
| |
| config CXL_REGION_INVALIDATION_TEST |
| bool "CXL: Region Cache Management Bypass (TEST)" |
| depends on CXL_REGION |
| help |
| CXL Region management and security operations potentially invalidate |
| the content of CPU caches without notifying those caches to |
| invalidate the affected cachelines. The CXL Region driver attempts |
| to invalidate caches when those events occur. If that invalidation |
| fails the region will fail to enable. Reasons for cache |
| invalidation failure are due to the CPU not providing a cache |
| invalidation mechanism. For example usage of wbinvd is restricted to |
| bare metal x86. However, for testing purposes toggling this option |
| can disable that data integrity safety and proceed with enabling |
| regions when there might be conflicting contents in the CPU cache. |
| |
| If unsure, or if this kernel is meant for production environments, |
| say N. |
| |
| endif |
