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+What: /sys/bus/cxl/flush
+Date: Januarry, 2022
+KernelVersion: v5.18
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (WO) If userspace manually unbinds a port the kernel schedules
+ all descendant memdevs for unbind. Writing '1' to this attribute
+ flushes that work.
+
+
+What: /sys/bus/cxl/devices/memX/firmware_version
+Date: December, 2020
+KernelVersion: v5.12
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) "FW Revision" string as reported by the Identify
+ Memory Device Output Payload in the CXL-2.0
+ specification.
+
+
+What: /sys/bus/cxl/devices/memX/ram/size
+Date: December, 2020
+KernelVersion: v5.12
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) "Volatile Only Capacity" as bytes. Represents the
+ identically named field in the Identify Memory Device Output
+ Payload in the CXL-2.0 specification.
+
+
+What: /sys/bus/cxl/devices/memX/pmem/size
+Date: December, 2020
+KernelVersion: v5.12
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) "Persistent Only Capacity" as bytes. Represents the
+ identically named field in the Identify Memory Device Output
+ Payload in the CXL-2.0 specification.
+
+
+What: /sys/bus/cxl/devices/memX/serial
+Date: January, 2022
+KernelVersion: v5.18
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) 64-bit serial number per the PCIe Device Serial Number
+ capability. Mandatory for CXL devices, see CXL 2.0 8.1.12.2
+ Memory Device PCIe Capabilities and Extended Capabilities.
+
+
+What: /sys/bus/cxl/devices/memX/numa_node
+Date: January, 2022
+KernelVersion: v5.18
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) If NUMA is enabled and the platform has affinitized the
+ host PCI device for this memory device, emit the CPU node
+ affinity for this device.
+
+
+What: /sys/bus/cxl/devices/memX/security/state
+Date: June, 2023
+KernelVersion: v6.5
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) Reading this file will display the CXL security state for
+ that device. Such states can be: 'disabled', 'sanitize', when
+ a sanitization is currently underway; or those available only
+ for persistent memory: 'locked', 'unlocked' or 'frozen'. This
+ sysfs entry is select/poll capable from userspace to notify
+ upon completion of a sanitize operation.
+
+
+What: /sys/bus/cxl/devices/memX/security/sanitize
+Date: June, 2023
+KernelVersion: v6.5
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (WO) Write a boolean 'true' string value to this attribute to
+ sanitize the device to securely re-purpose or decommission it.
+ This is done by ensuring that all user data and meta-data,
+ whether it resides in persistent capacity, volatile capacity,
+ or the LSA, is made permanently unavailable by whatever means
+ is appropriate for the media type. This functionality requires
+ the device to be disabled, that is, not actively decoding any
+ HPA ranges. This permits avoiding explicit global CPU cache
+ management, relying instead for it to be done when a region
+ transitions between software programmed and hardware committed
+ states. If this file is not present, then there is no hardware
+ support for the operation.
+
+
+What /sys/bus/cxl/devices/memX/security/erase
+Date: June, 2023
+KernelVersion: v6.5
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (WO) Write a boolean 'true' string value to this attribute to
+ secure erase user data by changing the media encryption keys for
+ all user data areas of the device. This functionality requires
+ the device to be disabled, that is, not actively decoding any
+ HPA ranges. This permits avoiding explicit global CPU cache
+ management, relying instead for it to be done when a region
+ transitions between software programmed and hardware committed
+ states. If this file is not present, then there is no hardware
+ support for the operation.
+
+
+What: /sys/bus/cxl/devices/memX/firmware/
+Date: April, 2023
+KernelVersion: v6.5
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Firmware uploader mechanism. The different files under
+ this directory can be used to upload and activate new
+ firmware for CXL devices. The interfaces under this are
+ documented in sysfs-class-firmware.
+
+
+What: /sys/bus/cxl/devices/*/devtype
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) CXL device objects export the devtype attribute which
+ mirrors the same value communicated in the DEVTYPE environment
+ variable for uevents for devices on the "cxl" bus.
+
+
+What: /sys/bus/cxl/devices/*/modalias
+Date: December, 2021
+KernelVersion: v5.18
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) CXL device objects export the modalias attribute which
+ mirrors the same value communicated in the MODALIAS environment
+ variable for uevents for devices on the "cxl" bus.
+
+
+What: /sys/bus/cxl/devices/portX/uport
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) CXL port objects are enumerated from either a platform
+ firmware device (ACPI0017 and ACPI0016) or PCIe switch upstream
+ port with CXL component registers. The 'uport' symlink connects
+ the CXL portX object to the device that published the CXL port
+ capability.
+
+
+What: /sys/bus/cxl/devices/{port,endpoint}X/parent_dport
+Date: January, 2023
+KernelVersion: v6.3
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) CXL port objects are instantiated for each upstream port in
+ a CXL/PCIe switch, and for each endpoint to map the
+ corresponding memory device into the CXL port hierarchy. When a
+ descendant CXL port (switch or endpoint) is enumerated it is
+ useful to know which 'dport' object in the parent CXL port
+ routes to this descendant. The 'parent_dport' symlink points to
+ the device representing the downstream port of a CXL switch that
+ routes to {port,endpoint}X.
+
+
+What: /sys/bus/cxl/devices/portX/dportY
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) CXL port objects are enumerated from either a platform
+ firmware device (ACPI0017 and ACPI0016) or PCIe switch upstream
+ port with CXL component registers. The 'dportY' symlink
+ identifies one or more downstream ports that the upstream port
+ may target in its decode of CXL memory resources. The 'Y'
+ integer reflects the hardware port unique-id used in the
+ hardware decoder target list.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) CXL decoder objects are enumerated from either a platform
+ firmware description, or a CXL HDM decoder register set in a
+ PCIe device (see CXL 2.0 section 8.2.5.12 CXL HDM Decoder
+ Capability Structure). The 'X' in decoderX.Y represents the
+ cxl_port container of this decoder, and 'Y' represents the
+ instance id of a given decoder resource.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/{start,size}
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) The 'start' and 'size' attributes together convey the
+ physical address base and number of bytes mapped in the
+ decoder's decode window. For decoders of devtype
+ "cxl_decoder_root" the address range is fixed. For decoders of
+ devtype "cxl_decoder_switch" the address is bounded by the
+ decode range of the cxl_port ancestor of the decoder's cxl_port,
+ and dynamically updates based on the active memory regions in
+ that address space.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/locked
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) CXL HDM decoders have the capability to lock the
+ configuration until the next device reset. For decoders of
+ devtype "cxl_decoder_root" there is no standard facility to
+ unlock them. For decoders of devtype "cxl_decoder_switch" a
+ secondary bus reset, of the PCIe bridge that provides the bus
+ for this decoders uport, unlocks / resets the decoder.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/target_list
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) Display a comma separated list of the current decoder
+ target configuration. The list is ordered by the current
+ configured interleave order of the decoder's dport instances.
+ Each entry in the list is a dport id.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/cap_{pmem,ram,type2,type3}
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) When a CXL decoder is of devtype "cxl_decoder_root", it
+ represents a fixed memory window identified by platform
+ firmware. A fixed window may only support a subset of memory
+ types. The 'cap_*' attributes indicate whether persistent
+ memory, volatile memory, accelerator memory, and / or expander
+ memory may be mapped behind this decoder's memory window.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/target_type
+Date: June, 2021
+KernelVersion: v5.14
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) When a CXL decoder is of devtype "cxl_decoder_switch", it
+ can optionally decode either accelerator memory (type-2) or
+ expander memory (type-3). The 'target_type' attribute indicates
+ the current setting which may dynamically change based on what
+ memory regions are activated in this decode hierarchy.
+
+
+What: /sys/bus/cxl/devices/endpointX/CDAT
+Date: July, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) If this sysfs entry is not present no DOE mailbox was
+ found to support CDAT data. If it is present and the length of
+ the data is 0 reading the CDAT data failed. Otherwise the CDAT
+ data is reported.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/mode
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) When a CXL decoder is of devtype "cxl_decoder_endpoint" it
+ translates from a host physical address range, to a device local
+ address range. Device-local address ranges are further split
+ into a 'ram' (volatile memory) range and 'pmem' (persistent
+ memory) range. The 'mode' attribute emits one of 'ram', 'pmem',
+ 'mixed', or 'none'. The 'mixed' indication is for error cases
+ when a decoder straddles the volatile/persistent partition
+ boundary, and 'none' indicates the decoder is not actively
+ decoding, or no DPA allocation policy has been set.
+
+ 'mode' can be written, when the decoder is in the 'disabled'
+ state, with either 'ram' or 'pmem' to set the boundaries for the
+ next allocation.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/dpa_resource
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) When a CXL decoder is of devtype "cxl_decoder_endpoint",
+ and its 'dpa_size' attribute is non-zero, this attribute
+ indicates the device physical address (DPA) base address of the
+ allocation.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/dpa_size
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) When a CXL decoder is of devtype "cxl_decoder_endpoint" it
+ translates from a host physical address range, to a device local
+ address range. The range, base address plus length in bytes, of
+ DPA allocated to this decoder is conveyed in these 2 attributes.
+ Allocations can be mutated as long as the decoder is in the
+ disabled state. A write to 'dpa_size' releases the previous DPA
+ allocation and then attempts to allocate from the free capacity
+ in the device partition referred to by 'decoderX.Y/mode'.
+ Allocate and free requests can only be performed on the highest
+ instance number disabled decoder with non-zero size. I.e.
+ allocations are enforced to occur in increasing 'decoderX.Y/id'
+ order and frees are enforced to occur in decreasing
+ 'decoderX.Y/id' order.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/interleave_ways
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) The number of targets across which this decoder's host
+ physical address (HPA) memory range is interleaved. The device
+ maps every Nth block of HPA (of size ==
+ 'interleave_granularity') to consecutive DPA addresses. The
+ decoder's position in the interleave is determined by the
+ device's (endpoint or switch) switch ancestry. For root
+ decoders their interleave is specified by platform firmware and
+ they only specify a downstream target order for host bridges.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/interleave_granularity
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) The number of consecutive bytes of host physical address
+ space this decoder claims at address N before the decode rotates
+ to the next target in the interleave at address N +
+ interleave_granularity (assuming N is aligned to
+ interleave_granularity).
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/create_{pmem,ram}_region
+Date: May, 2022, January, 2023
+KernelVersion: v6.0 (pmem), v6.3 (ram)
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Write a string in the form 'regionZ' to start the process
+ of defining a new persistent, or volatile memory region
+ (interleave-set) within the decode range bounded by root decoder
+ 'decoderX.Y'. The value written must match the current value
+ returned from reading this attribute. An atomic compare exchange
+ operation is done on write to assign the requested id to a
+ region and allocate the region-id for the next creation attempt.
+ EBUSY is returned if the region name written does not match the
+ current cached value.
+
+
+What: /sys/bus/cxl/devices/decoderX.Y/delete_region
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (WO) Write a string in the form 'regionZ' to delete that region,
+ provided it is currently idle / not bound to a driver.
+
+
+What: /sys/bus/cxl/devices/regionZ/uuid
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Write a unique identifier for the region. This field must
+ be set for persistent regions and it must not conflict with the
+ UUID of another region. For volatile ram regions this
+ attribute is a read-only empty string.
+
+
+What: /sys/bus/cxl/devices/regionZ/interleave_granularity
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Set the number of consecutive bytes each device in the
+ interleave set will claim. The possible interleave granularity
+ values are determined by the CXL spec and the participating
+ devices.
+
+
+What: /sys/bus/cxl/devices/regionZ/interleave_ways
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Configures the number of devices participating in the
+ region is set by writing this value. Each device will provide
+ 1/interleave_ways of storage for the region.
+
+
+What: /sys/bus/cxl/devices/regionZ/size
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) System physical address space to be consumed by the region.
+ When written trigger the driver to allocate space out of the
+ parent root decoder's address space. When read the size of the
+ address space is reported and should match the span of the
+ region's resource attribute. Size shall be set after the
+ interleave configuration parameters. Once set it cannot be
+ changed, only freed by writing 0. The kernel makes no guarantees
+ that data is maintained over an address space freeing event, and
+ there is no guarantee that a free followed by an allocate
+ results in the same address being allocated.
+
+
+What: /sys/bus/cxl/devices/regionZ/mode
+Date: January, 2023
+KernelVersion: v6.3
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) The mode of a region is established at region creation time
+ and dictates the mode of the endpoint decoder that comprise the
+ region. For more details on the possible modes see
+ /sys/bus/cxl/devices/decoderX.Y/mode
+
+
+What: /sys/bus/cxl/devices/regionZ/resource
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) A region is a contiguous partition of a CXL root decoder
+ address space. Region capacity is allocated by writing to the
+ size attribute, the resulting physical address space determined
+ by the driver is reflected here. It is therefore not useful to
+ read this before writing a value to the size attribute.
+
+
+What: /sys/bus/cxl/devices/regionZ/target[0..N]
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Write an endpoint decoder object name to 'targetX' where X
+ is the intended position of the endpoint device in the region
+ interleave and N is the 'interleave_ways' setting for the
+ region. ENXIO is returned if the write results in an impossible
+ to map decode scenario, like the endpoint is unreachable at that
+ position relative to the root decoder interleave. EBUSY is
+ returned if the position in the region is already occupied, or
+ if the region is not in a state to accept interleave
+ configuration changes. EINVAL is returned if the object name is
+ not an endpoint decoder. Once all positions have been
+ successfully written a final validation for decode conflicts is
+ performed before activating the region.
+
+
+What: /sys/bus/cxl/devices/regionZ/commit
+Date: May, 2022
+KernelVersion: v6.0
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Write a boolean 'true' string value to this attribute to
+ trigger the region to transition from the software programmed
+ state to the actively decoding in hardware state. The commit
+ operation in addition to validating that the region is in proper
+ configured state, validates that the decoders are being
+ committed in spec mandated order (last committed decoder id +
+ 1), and checks that the hardware accepts the commit request.
+ Reading this value indicates whether the region is committed or
+ not.
+
+
+What: /sys/bus/cxl/devices/memX/trigger_poison_list
+Date: April, 2023
+KernelVersion: v6.4
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (WO) When a boolean 'true' is written to this attribute the
+ memdev driver retrieves the poison list from the device. The
+ list consists of addresses that are poisoned, or would result
+ in poison if accessed, and the source of the poison. This
+ attribute is only visible for devices supporting the
+ capability. The retrieved errors are logged as kernel
+ events when cxl_poison event tracing is enabled.