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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/ABI/testing/sysfs-bus-cxl
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
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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/*/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/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: v5.20
+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: v5.20
+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: v5.20
+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: v5.20
+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: v5.20
+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: v5.20
+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_region
+Date: May, 2022
+KernelVersion: v5.20
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Write a string in the form 'regionZ' to start the process
+ of defining a new persistent 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: v5.20
+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: v5.20
+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.
+
+
+What: /sys/bus/cxl/devices/regionZ/interleave_granularity
+Date: May, 2022
+KernelVersion: v5.20
+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: v5.20
+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: v5.20
+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/resource
+Date: May, 2022
+KernelVersion: v5.20
+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: v5.20
+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: v5.20
+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.