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# SPDX-License-Identifier: GPL-2.0-only
menuconfig CXL_BUS
tristate "CXL (Compute Express Link) Devices Support"
depends on PCI
CXL is a bus that is electrically compatible with PCI Express, but
layers three protocols on that signalling (, 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 protocol is equivalent to PCI Express.
Say 'y' to enable support for the configuration and management of
devices supporting these protocols.
config CXL_MEM
tristate "CXL.mem: Memory Devices"
default CXL_BUS
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 was attached to the typical CPU memory
Say 'y/m' to enable a driver that will attach to CXL.mem devices 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
If unsure say 'm'.
bool "RAW Command Interface for Memory Devices"
depends on CXL_MEM
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
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)
( 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
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'.