[PATCH 2/3] nvmet: add ABI documentation for target configfs interfaces
Hannes Reinecke
hare at suse.de
Wed Jul 1 23:35:40 PDT 2026
On 7/2/26 5:48 AM, Guixin Liu wrote:
> Add Documentation/ABI/testing/configfs-nvmet documenting all NVMe
> target configfs attributes, covering port attributes, subsystem
> attributes, namespace attributes, host authentication, passthrough
> mode, and ANA configuration.
>
> Each entry has been traced to its original introducing commit to
> provide accurate Date, KernelVersion, and Contact information.
>
> Signed-off-by: Guixin Liu <kanie at linux.alibaba.com>
> ---
> Documentation/ABI/testing/configfs-nvmet | 347 +++++++++++++++++++++++
> 1 file changed, 347 insertions(+)
> create mode 100644 Documentation/ABI/testing/configfs-nvmet
>
> diff --git a/Documentation/ABI/testing/configfs-nvmet b/Documentation/ABI/testing/configfs-nvmet
> new file mode 100644
> index 000000000000..728c905310c5
> --- /dev/null
> +++ b/Documentation/ABI/testing/configfs-nvmet
> @@ -0,0 +1,347 @@
> +What: /config/nvmet/ports/N/addr_adrfam
> +What: /config/nvmet/ports/N/addr_portid
> +What: /config/nvmet/ports/N/addr_traddr
> +What: /config/nvmet/ports/N/addr_trsvcid
> +What: /config/nvmet/ports/N/addr_trtype
> +What: /config/nvmet/ports/N/addr_treq
> +Date: June 2016
> +KernelVersion: 4.8
> +Contact: Christoph Hellwig <hch at lst.de>
> +Description:
> + Address attributes for an NVMe-oF target port.
> +
> + addr_adrfam: Shows or sets the address family. Accepted
> + values: "pcie", "ipv4", "ipv6", "ib", "fc", "pci", "loop".
> +
> + addr_portid: Shows or sets the port identifier (u16).
> +
> + addr_traddr: Shows or sets the transport address string.
> +
> + addr_trsvcid: Shows or sets the transport service identifier.
> +
> + addr_trtype: Shows or sets the transport type. Accepted
> + values: "rdma", "fc", "tcp", "pci", "loop". Also
> + initializes default TSAS values.
> +
> + addr_treq: Shows or sets the transport security requirements.
> + Accepted values: "not specified", "required",
> + "not required". For TCP with TLS1.3, "not specified" is
> + rejected.
> +
> + All attributes require the port to be disabled before
> + modification.
> +
> +What: /config/nvmet/ports/N/referrals/NAME/addr_adrfam
> +What: /config/nvmet/ports/N/referrals/NAME/addr_portid
> +What: /config/nvmet/ports/N/referrals/NAME/addr_traddr
> +What: /config/nvmet/ports/N/referrals/NAME/addr_trsvcid
> +What: /config/nvmet/ports/N/referrals/NAME/addr_trtype
> +What: /config/nvmet/ports/N/referrals/NAME/addr_treq
> +What: /config/nvmet/ports/N/referrals/NAME/enable
> +Date: June 2016
> +KernelVersion: 4.8
> +Contact: Christoph Hellwig <hch at lst.de>
> +Description:
> + Address attributes and enable control for a referral entry
> + under a port. The addr_* attributes have the same semantics
> + as the corresponding port-level attributes. The enable
> + attribute shows or sets whether this referral is enabled
> + (boolean).
> +
> +What: /config/nvmet/subsystems/NAME/attr_allow_any_host
> +Date: June 2016
> +KernelVersion: 4.8
> +Contact: Christoph Hellwig <hch at lst.de>
> +Description:
> + Shows or sets whether any host is allowed to connect.
> + Accepts boolean value. Cannot be set to 1 if explicit
> + hosts are linked in the allowed_hosts/ directory.
> +
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/device_path
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/device_nguid
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/enable
> +Date: June 2016
> +KernelVersion: 4.8
> +Contact: Christoph Hellwig <hch at lst.de>
> +Description:
> + Namespace attributes added with the initial NVMe target.
> +
> + device_path: Shows or sets the backend block device path.
> + The namespace must be disabled before modification.
> +
> + device_nguid: Shows or sets the NGUID (128-bit identifier).
> + Accepts 32 hex digits with optional "-" or ":" separators.
> + The namespace must be disabled before modification.
> +
> + enable: Shows or sets whether this namespace is enabled
> + (boolean).
> +
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/device_uuid
> +Date: June 2017
> +KernelVersion: 4.13
> +Contact: Johannes Thumshirn <jthumshirn at suse.de>
> +Description:
> + Shows or sets the UUID for this namespace. The namespace
> + must be disabled before modification.
> +
> +What: /config/nvmet/subsystems/NAME/attr_version
> +What: /config/nvmet/subsystems/NAME/attr_serial
> +Date: July 2017
> +KernelVersion: 4.13
> +Contact: Johannes Thumshirn <jthumshirn at suse.de>
> +Description:
> + attr_version: Shows or sets the NVMe version reported by
> + this subsystem. Format: "major.minor" or
> + "major.minor.tertiary". Cannot be changed after the
> + subsystem has been discovered.
> +
> + attr_serial: Shows or sets the serial number. Must be a
> + 1-20 byte ASCII string (characters 0x20-0x7e). Cannot be
> + changed after the subsystem has been discovered.
> +
> +What: /config/nvmet/ports/N/ana_groups/ID/ana_state
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/ana_grpid
> +Date: June 2018
> +KernelVersion: 4.19
> +Contact: Christoph Hellwig <hch at lst.de>
> +Description:
> + ANA (Asymmetric Namespace Access) attributes.
> +
> + ana_state: Shows or sets the ANA state for this group on
> + this port. Accepted values: "optimized", "non-optimized",
> + "inaccessible", "persistent-loss", "change". Changes
> + trigger an ANA change event.
> +
> + ana_grpid: Shows or sets the ANA Group ID for this
> + namespace. Must be between 1 and 128. Changing triggers
> + an ANA event notification.
> +
> +What: /config/nvmet/ports/N/param_inline_data_size
> +Date: June 2018
> +KernelVersion: 4.19
> +Contact: Steve Wise <swise at opengridcomputing.com>
> +Description:
> + Shows or sets the inline data size for this port. Default
> + is -1 which lets the transport choose. The port must be
> + disabled before modification.
> +
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/buffered_io
> +Date: June 2018
> +KernelVersion: 4.19
> +Contact: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> +Description:
> + Shows or sets whether buffered I/O is used for this
> + namespace. Accepts boolean value. The namespace must be
> + disabled before modification.
> +
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/p2pmem
> +Date: October 2018
> +KernelVersion: 4.20
> +Contact: Logan Gunthorpe <logang at deltatee.com>
> +Description:
> + Shows or sets the P2P DMA memory device for this namespace.
> + Accepts a PCI device BDF, "auto", or "none". The namespace
> + must be disabled before modification. Only available when
> + CONFIG_PCI_P2PDMA is enabled.
> +
> +What: /config/nvmet/subsystems/NAME/attr_cntlid_min
> +What: /config/nvmet/subsystems/NAME/attr_cntlid_max
> +Date: January 2020
> +KernelVersion: 5.7
> +Contact: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> +Description:
> + attr_cntlid_min: Shows or sets the minimum controller ID
> + (u16). Must be nonzero and not greater than attr_cntlid_max.
> +
> + attr_cntlid_max: Shows or sets the maximum controller ID
> + (u16). Must be nonzero and not less than attr_cntlid_min.
> +
> +What: /config/nvmet/subsystems/NAME/attr_model
> +Date: January 2020
> +KernelVersion: 5.7
> +Contact: Mark Ruijter <MRuijter at onestopsystems.com>
> +Description:
> + Shows or sets the model number for this subsystem. Must
> + be a 1-40 byte ASCII string (characters 0x20-0x7e).
> + Cannot be changed after the subsystem has been discovered.
> +
> +What: /config/nvmet/subsystems/NAME/attr_pi_enable
> +What: /config/nvmet/ports/N/param_pi_enable
> +Date: May 2020
> +KernelVersion: 5.8
> +Contact: Israel Rukshin <israelr at mellanox.com>
> +Description:
> + Shows or sets whether protection information (PI) is
> + enabled/supported. Accepts boolean value. Only available
> + when CONFIG_BLK_DEV_INTEGRITY is enabled. The port-level
> + attribute requires the port to be disabled before
> + modification.
> +
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/revalidate_size
> +Date: May 2020
> +KernelVersion: 5.8
> +Contact: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> +Description:
> + Write-only. Writing 1 triggers namespace size revalidation.
> + If the size has changed, a namespace changed AEN is sent.
> + The namespace must be enabled.
> +
> +What: /config/nvmet/subsystems/NAME/passthru/device_path
> +What: /config/nvmet/subsystems/NAME/passthru/enable
> +Date: July 2020
> +KernelVersion: 5.9
> +Contact: Logan Gunthorpe <logang at deltatee.com>
> +Description:
> + Passthrough mode attributes.
> +
> + device_path: Shows or sets the NVMe controller character
> + device path (e.g., /dev/nvme0). Cannot be changed while
> + the passthrough controller is active.
> +
> + enable: Shows or sets whether passthrough mode is enabled
> + (boolean).
> +
> + Only available when CONFIG_NVME_TARGET_PASSTHRU is enabled.
> +
> +What: /config/nvmet/subsystems/NAME/passthru/admin_timeout
> +What: /config/nvmet/subsystems/NAME/passthru/io_timeout
> +Date: November 2020
> +KernelVersion: 5.11
> +Contact: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> +Description:
> + admin_timeout: Shows or sets the admin command timeout for
> + passthrough mode, in jiffies.
> +
> + io_timeout: Shows or sets the I/O command timeout for
> + passthrough mode, in jiffies.
> +
> + Only available when CONFIG_NVME_TARGET_PASSTHRU is enabled.
> +
> +What: /config/nvmet/subsystems/NAME/passthru/clear_ids
> +Date: June 2022
> +KernelVersion: 5.19
> +Contact: Alan Adamson <alan.adamson at oracle.com>
> +Description:
> + Shows or sets whether to clear identify data IDs in
> + passthrough mode. Only available when
> + CONFIG_NVME_TARGET_PASSTHRU is enabled.
> +
> +What: /config/nvmet/hosts/HOSTNQN/dhchap_key
> +What: /config/nvmet/hosts/HOSTNQN/dhchap_ctrl_key
> +What: /config/nvmet/hosts/HOSTNQN/dhchap_hash
> +Date: June 2022
> +KernelVersion: 6.0
> +Contact: Hannes Reinecke <hare at suse.de>
> +Description:
> + DH-HMAC-CHAP authentication attributes.
> +
> + dhchap_key: Shows or sets the host secret key. Accepts a
> + key string in "DHHC-1:" format.
> +
> + dhchap_ctrl_key: Shows or sets the controller secret key
> + for bidirectional authentication. Same format as dhchap_key.
> +
> + dhchap_hash: Shows or sets the HMAC hash algorithm.
> + Accepted values: "hmac(sha256)", "hmac(sha384)",
> + "hmac(sha512)".
> +
> + Only available when CONFIG_NVME_TARGET_AUTH is enabled.
> +
> +What: /config/nvmet/hosts/HOSTNQN/dhchap_dhgroup
> +Date: June 2022
> +KernelVersion: 6.0
> +Contact: Hannes Reinecke <hare at suse.de>
> +Description:
> + Shows or sets the Diffie-Hellman group for DH-HMAC-CHAP
> + key exchange. Accepted values: "null", "ffdhe2048",
> + "ffdhe3072", "ffdhe4096", "ffdhe6144". Non-null groups
> + require the corresponding KPP crypto algorithm to be
> + available. Only available when CONFIG_NVME_TARGET_AUTH
> + is enabled.
> +
Why is this a separate entry, and not grouped with the other dhchap
entries?
And these are 'host' settings. Please keep settings for 'host',
'subsystem', and 'ports' together.
> +What: /config/nvmet/subsystems/NAME/attr_qid_max
> +Date: August 2022
> +KernelVersion: 6.1
> +Contact: Daniel Wagner <dwagner at suse.de>
> +Description:
> + Shows or sets the maximum queue ID (number of I/O queues,
> + u16). Must be between 1 and 128. Changing this value
> + forces reconnection of all connected controllers.
> +
> +What: /config/nvmet/subsystems/NAME/attr_ieee_oui
> +Date: November 2022
> +KernelVersion: 6.2
> +Contact: Aleksandr Miloserdov <a.miloserdov at yadro.com>
> +Description:
> + Shows or sets the IEEE OUI for this subsystem. Displayed
> + in "0x%06x" format. Must be a 24-bit value. Cannot be
> + changed after the subsystem has been discovered.
> +
> +What: /config/nvmet/subsystems/NAME/attr_firmware
> +Date: November 2022
> +KernelVersion: 6.2
> +Contact: Aleksandr Miloserdov <a.miloserdov at yadro.com>
> +Description:
> + Shows or sets the firmware revision string for this
> + subsystem. Must be a 1-8 byte ASCII string (characters
> + 0x20-0x7e). Cannot be changed after the subsystem has
> + been discovered.
> +
> +What: /config/nvmet/ports/N/addr_tsas
> +Date: August 2023
> +KernelVersion: 6.7
> +Contact: Hannes Reinecke <hare at suse.de>
> +Description:
> + Shows or sets the transport-specific address subtype. For
> + TCP transport, accepted values: "none", "tls1.3" (requires
> + CONFIG_NVME_TARGET_TCP_TLS). For RDMA transport, shows the
> + QP type: "connected" or "datagram". The port must be
> + disabled before modification.
> +
> +What: /config/nvmet/ports/N/param_max_queue_size
> +Date: January 2024
> +KernelVersion: 6.9
> +Contact: Max Gurtovoy <mgurtovoy at nvidia.com>
> +Description:
> + Shows or sets the maximum queue size for this port. Default
> + is -1 which lets the transport choose. The port must be
> + disabled before modification.
> +
> +What: /config/nvmet/discovery_nqn
> +Date: April 2024
> +KernelVersion: 6.9
> +Contact: Hannes Reinecke <hare at kernel.org>
> +Description:
> + Shows or sets the NQN of the discovery subsystem. The
> + value must be unique and not duplicate any existing
> + subsystem name.
> +
> +What: /config/nvmet/subsystems/NAME/namespaces/NSID/resv_enable
> +Date: November 2024
> +KernelVersion: 6.13
> +Contact: Guixin Liu <kanie at linux.alibaba.com>
> +Description:
> + Shows or sets whether persistent reservation support is
> + enabled for this namespace. Accepts boolean value. The
> + namespace must be disabled before modification.
> +
> +What: /config/nvmet/subsystems/NAME/attr_vendor_id
> +What: /config/nvmet/subsystems/NAME/attr_subsys_vendor_id
> +Date: January 2025
> +KernelVersion: 6.14
> +Contact: Damien Le Moal <dlemoal at kernel.org>
> +Description:
> + attr_vendor_id: Shows or sets the PCI vendor ID reported
> + by this subsystem. Displayed in "0x%x" format.
> +
> + attr_subsys_vendor_id: Shows or sets the PCI subsystem
> + vendor ID. Displayed in "0x%x" format.
> +
> +What: /config/nvmet/ports/N/param_mdts
> +Date: April 2026
> +KernelVersion: 7.1
> +Contact: Aurelien Aptel <aaptel at nvidia.com>
> +Description:
> + Shows or sets the maximum data transfer size for this port.
> + Default is -1 which lets the transport choose. The port
> + must be disabled before modification.
Otherwise looks good.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare at suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
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