libnvme(2)

📦
version 1.16.2 · 14 versions
, in ubuntu stonking

🌸 NAME 🌸

okay bestie, welcome to libnvme(2) — the API Manual page for struct nvme_id_ctrl, aka the Identify Controller data structure. This is the big identity struct for an NVMe controller, and we're going through every single field, no skips, no crumbs. 💅

✨ SYNOPSIS ✨

here's the whole struct, copied exactly, no edits, no vibe-based rewriting inside the code block:

struct nvme_id_ctrl {
    __le16 vid;
    __le16 ssvid;
    char sn[20];
    char mn[40];
    char fr[8];
    __u8 rab;
    __u8 ieee[3];
    __u8 cmic;
    __u8 mdts;
    __le16 cntlid;
    __le32 ver;
    __le32 rtd3r;
    __le32 rtd3e;
    __le32 oaes;
    __le32 ctratt;
    __le16 rrls;
    __u8 bpcap;
    __u8 rsvd103;
    __le32 nssl;
    __u8 rsvd108[2];
    __u8 plsi;
    __u8 cntrltype;
    __u8 fguid[16];
    __le16 crdt1;
    __le16 crdt2;
    __le16 crdt3;
    __u8 crcap;
    __u8 rsvd135[118];
    __u8 nvmsr;
    __u8 vwci;
    __u8 mec;
    __le16 oacs;
    __u8 acl;
    __u8 aerl;
    __u8 frmw;
    __u8 lpa;
    __u8 elpe;
    __u8 npss;
    __u8 avscc;
    __u8 apsta;
    __le16 wctemp;
    __le16 cctemp;
    __le16 mtfa;
    __le32 hmpre;
    __le32 hmmin;
    __u8 tnvmcap[16];
    __u8 unvmcap[16];
    __le32 rpmbs;
    __le16 edstt;
    __u8 dsto;
    __u8 fwug;
    __le16 kas;
    __le16 hctma;
    __le16 mntmt;
    __le16 mxtmt;
    __le32 sanicap;
    __le32 hmminds;
    __le16 hmmaxd;
    __le16 nsetidmax;
    __le16 endgidmax;
    __u8 anatt;
    __u8 anacap;
    __le32 anagrpmax;
    __le32 nanagrpid;
    __le32 pels;
    __le16 domainid;
    __u8 kpioc;
    __u8 rsvd359;
    __le16 mptfawr;
    __u8 rsvd362[6];
    __u8 megcap[16];
    __u8 tmpthha;
    __u8 rsvd385;
    __le16 cqt;
    __u8 rsvd388[124];
    __u8 sqes;
    __u8 cqes;
    __le16 maxcmd;
    __le32 nn;
    __le16 oncs;
    __le16 fuses;
    __u8 fna;
    __u8 vwc;
    __le16 awun;
    __le16 awupf;
    __u8 icsvscc;
    __u8 nwpc;
    __le16 acwu;
    __le16 ocfs;
    __le32 sgls;
    __le32 mnan;
    __u8 maxdna[16];
    __le32 maxcna;
    __le32 oaqd;
    __u8 rhiri;
    __u8 hirt;
    __le16 cmmrtd;
    __le16 nmmrtd;
    __u8 minmrtg;
    __u8 maxmrtg;
    __u8 trattr;
    __u8 rsvd577;
    __le16 mcudmq;
    __le16 mnsudmq;
    __le16 mcmr;
    __le16 nmcmr;
    __le16 mcdqpc;
    __u8 rsvd588[180];
    char subnqn[NVME_NQN_LENGTH];
    __u8 rsvd1024[768];
    __le32 ioccsz;
    __le32 iorcsz;
    __le16 icdoff;
    __u8 fcatt;
    __u8 msdbd;
    __le16 ofcs;
    __u8 dctype;
    __u8 rsvd1807[241];
    struct nvme_id_psd      psd[32];
    __u8 vs[1024];
 };

👑 Members 👑

okay so every field gets its own moment. I'm listing them all, fr fr, with the exact meaning from the page. 🫶

  • vid — PCI Vendor ID, the company vendor identifier that is assigned by the PCI SIG.
  • ssvid — PCI Subsystem Vendor ID, the company vendor identifier that is assigned by the PCI SIG for the subsystem.
  • sn — Serial Number in ASCII.
  • mn — Model Number in ASCII.
  • fr — Firmware Revision in ASCII, the currently active firmware revision for the NVM subsystem.
  • rab — Recommended Arbitration Burst, reported as a power of two.
  • ieee — IEEE assigned Organization Unique Identifier.
  • cmic — Controller Multipath IO and Namespace Sharing Capabilities of the controller and NVM subsystem. See enum nvme_id_ctrl_cmic.
  • mdts — Max Data Transfer Size is the largest data transfer size. The host should not submit a command that exceeds this maximum data transfer size. The value is in units of the minimum memory page size (CAP.MPSMIN) and is reported as a power of two.
  • cntlid — Controller ID, the NVM subsystem unique controller identifier associated with the controller.
  • ver — Version, this field contains the value reported in the Version register, or property (see enum nvme_registers NVME_REG_VS).
  • rtd3r — RTD3 Resume Latency, the expected latency in microseconds to resume from Runtime D3.
  • rtd3e — RTD3 Exit Latency, the typical latency in microseconds to enter Runtime D3.
  • oaes — Optional Async Events Supported, see enum nvme_id_ctrl_oaes.
  • ctratt — Controller Attributes, see enum nvme_id_ctrl_ctratt.
  • rrls — Read Recovery Levels. If a bit is set, then the corresponding Read Recovery Level is supported. If a bit is cleared, then the corresponding Read Recovery Level is not supported.
  • bpcap — Boot Partition Capabilities, see enum nvme_id_ctrl_bpcap.
  • rsvd103 — Reserved.
  • nssl — NVM Subsystem Shutdown Latency (NSSL). This field indicates the typical latency in microseconds for an NVM Subsystem Shutdown to complete.
  • rsvd108 — Reserved.
  • plsi — Power Loss Signaling Information (PLSI), see enum nvme_id_ctrl_plsi.
  • cntrltype — Controller Type, see enum nvme_id_ctrl_cntrltype.
  • fguid — FRU GUID, a 128-bit value that is globally unique for a given Field Replaceable Unit.
  • crdt1 — Controller Retry Delay time in 100 millisecond units if CQE CRD field is 1.
  • crdt2 — Controller Retry Delay time in 100 millisecond units if CQE CRD field is 2.
  • crdt3 — Controller Retry Delay time in 100 millisecond units if CQE CRD field is 3.
  • crcap — Controller Reachability Capabilities (CRCAP), see enum nvme_id_ctrl_crcap.
  • rsvd135 — Reserved.
  • nvmsr — NVM Subsystem Report, see enum nvme_id_ctrl_nvmsr.
  • vwci — VPD Write Cycle Information, see enum nvme_id_ctrl_vwci.
  • mec — Management Endpoint Capabilities, see enum nvme_id_ctrl_mec.
  • oacs — Optional Admin Command Support, the optional Admin commands and features supported by the controller, see enum nvme_id_ctrl_oacs.
  • acl — Abort Command Limit, the maximum number of concurrently executing Abort commands supported by the controller. This is a 0's based value.
  • aerl — Async Event Request Limit, the maximum number of concurrently outstanding Asynchronous Event Request commands supported by the controller. This is a 0's based value.
  • frmw — Firmware Updates indicates capabilities regarding firmware updates. See enum nvme_id_ctrl_frmw.
  • lpa — Log Page Attributes, see enum nvme_id_ctrl_lpa.
  • elpe — Error Log Page Entries, the maximum number of Error Information log entries that are stored by the controller. This field is a 0's based value.
  • npss — Number of Power States Supported, the number of NVM Express power states supported by the controller, indicating the number of valid entries in struct nvme_id_ctrl.psd. This is a 0's based value.
  • avscc — Admin Vendor Specific Command Configuration, see enum nvme_id_ctrl_avscc.
  • apsta — Autonomous Power State Transition Attributes, see enum nvme_id_ctrl_apsta.
  • wctemp — Warning Composite Temperature Threshold indicates the minimum Composite Temperature field value (see struct nvme_smart_log.critical_comp_time) that indicates an overheating condition during which controller operation continues.
  • cctemp — Critical Composite Temperature Threshold, field indicates the minimum Composite Temperature field value (see struct nvme_smart_log.critical_comp_time) that indicates a critical overheating condition.
  • mtfa — Maximum Time for Firmware Activation indicates the maximum time the controller temporarily stops processing commands to activate the firmware image, specified in 100 millisecond units. This field is always valid if the controller supports firmware activation without a reset.
  • hmpre — Host Memory Buffer Preferred Size indicates the preferred size that the host is requested to allocate for the Host Memory Buffer feature in 4 KiB units.
  • hmmin — Host Memory Buffer Minimum Size indicates the minimum size that the host is requested to allocate for the Host Memory Buffer feature in 4 KiB units.
  • tnvmcap — Total NVM Capacity, the total NVM capacity in the NVM subsystem. The value is in bytes.
  • unvmcap — Unallocated NVM Capacity, the unallocated NVM capacity in the NVM subsystem. The value is in bytes.
  • rpmbs — Replay Protected Memory Block Support, see enum nvme_id_ctrl_rpmbs.
  • edstt — Extended Device Self-test Time, if Device Self-test command is supported (see struct nvme_id_ctrl.oacs, NVME_CTRL_OACS_SELF_TEST), then this field indicates the nominal amount of time in one minute units that the controller takes to complete an extended device self-test operation when in power state 0.
  • dsto — Device Self-test Options, see enum nvme_id_ctrl_dsto.
  • fwug — Firmware Update Granularity indicates the granularity and alignment requirement of the firmware image being updated by the Firmware Image Download command. The value is reported in 4 KiB units. A value of 0h indicates no information on granularity is provided. A value of FFh indicates no restriction.
  • kas — Keep Alive Support indicates the granularity of the Keep Alive Timer in 100 millisecond units.
  • hctma — Host Controlled Thermal Management Attributes, see enum nvme_id_ctrl_hctm.
  • mntmt — Minimum Thermal Management Temperature indicates the minimum temperature, in degrees Kelvin, that the host may request in the Thermal Management Temperature 1 field and Thermal Management Temperature 2 field of a Set Features command with the Feature Identifier field set to NVME_FEAT_FID_HCTM.
  • mxtmt — Maximum Thermal Management Temperature indicates the maximum temperature, in degrees Kelvin, that the host may request in the Thermal Management Temperature 1 field and Thermal Management Temperature 2 field of the Set Features command with the Feature Identifier set to NVME_FEAT_FID_HCTM.
  • sanicap — Sanitize Capabilities, see enum nvme_id_ctrl_sanicap.
  • hmminds — Host Memory Buffer Minimum Descriptor Entry Size, and it's literally telling you the minimum usable size of a Host Memory Buffer Descriptor Entry 🎀 measured in 4 KiB units, so do the math in 4 KiB chunks bestie.
  • hmmaxd — Host Memory Maximum Descriptors Entries, aka the number of usable Host Memory Buffer Descriptor Entries you actually get to play with.
  • nsetidmax — NVM Set Identifier Maximum: defines the maximum value of a valid NVM Set Identifier for any controller in the NVM subsystem ✨
  • endgidmax — Endurance Group Identifier Maximum: defines the maximum value of a valid Endurance Group Identifier for any controller in the NVM subsystem. same energy, different identifier 💅
  • anatt — ANA Transition Time. It indicates the maximum amount of time, in seconds, for a transition between ANA states, or the maximum amount of time, in seconds, that the controller reports the ANA change state ⏳
  • anacap — Asymmetric Namespace Access Capabilities. go look at enum nvme_id_ctrl_anacap for the deets 🔍
  • anagrpmax — ANA Group Identifier Maximum: indicates the maximum value of a valid ANA Group Identifier for any controller in the NVM subsystem.
  • nanagrpid — Number of ANA Group Identifiers: indicates the number of ANA groups supported by this controller 🌈
  • pels — Persistent Event Log Size: indicates the maximum reportable size for the Persistent Event Log 📜
  • domainid — Domain Identifier: indicates the identifier of the domain that contains this controller.
  • kpioc — Key Per I/O Capabilities (KPIOC). see enum nvme_id_ctrl_kpioc 🔑
  • rsvd359 — Reserved 🙈 (it's reserved, nothing to see here, move along)
  • mptfawr — Maximum Processing Time for Firmware Activation Without Reset (MPTFAWR). This field shall indicate the estimated maximum time in 100 ms units required by the controller to process a Firmware Commit command that specifies a value of 011b in the Commit Action field. yes it's a mouthful, it ate 💅
  • rsvd362 — Reserved 💀
  • megcap — Max Endurance Group Capacity: indicates the maximum capacity of a single Endurance Group.
  • tmpthha — Temperature Threshold Hysteresis Attributes 🌡️
  • rsvd385 — Reserved 💀
  • cqt — Command Quiesce Time (CQT). This field indicates the expected worst-case time in 1 millisecond units for the controller to quiesce all outstanding commands after a Keep Alive Timeout or other communication loss. the way it just... waits, then quiesces 😭
  • rsvd388 — Reserved 💀
  • sqes — Submission Queue Entry Size. see enum nvme_id_ctrl_sqes ✨
  • cqes — Completion Queue Entry Size. see enum nvme_id_ctrl_cqes ✨
  • maxcmd — Maximum Outstanding Commands: indicates the maximum number of commands that the controller processes at one time for a particular queue. one at a time per queue, we love a focused icon 🫶
  • nn — Number of Namespaces: indicates the maximum value of a valid nsid for the NVM subsystem. If the MNAN (struct nvme_id_ctrl.mnan) field is cleared to 0h, then this field also indicates the maximum number of namespaces supported by the NVM subsystem. two answers for the price of one, no cap.
  • oncs — Optional NVM Command Support. see enum nvme_id_ctrl_oncs 🎀
  • fuses — Fused Operation Support. see enum nvme_id_ctrl_fuses 🔥 (fuses, fire, coincidence? maybe)
  • fna — Format NVM Attributes. see enum nvme_id_ctrl_fna.
  • vwc — Volatile Write Cache. see enum nvme_id_ctrl_vwc. it's giving volatile, as in don't-trust-it-with-your-life 💀
  • awun — Atomic Write Unit Normal: indicates the size of the write operation guaranteed to be written atomically to the NVM across all namespaces with any supported namespace format during normal operation. This field is specified in logical blocks and is a 0's based value.
  • awupf — Atomic Write Unit Power Fail: indicates the size of the write operation guaranteed to be written atomically to the NVM across all namespaces with any supported namespace format during a power fail or error condition. This field is specified in logical blocks and is a 0's based value. same guarantees, but the lights just went out ⚡
  • icsvscc — NVM Vendor Specific Command Configuration. see enum nvme_id_ctrl_nvscc.
  • nwpc — Namespace Write Protection Capabilities. see enum nvme_id_ctrl_nwpc 🛡️
  • acwu — Atomic Compare & Write Unit: indicates the size of the write operation guaranteed to be written atomically to the NVM across all namespaces with any supported namespace format for a Compare and Write fused operation. This field is specified in logical blocks and is a 0's based value.
  • ocfs — Optional Copy Formats Supported: each bit n means the controller supports Copy Format n ✨ bit by bit, we love an index.
  • sgls — SGL Support. see enum nvme_id_ctrl_sgls 🦋
  • mnan — Maximum Number of Allowed Namespaces: indicates the maximum number of namespaces supported by the NVM subsystem.
  • maxdna — Maximum Domain Namespace Attachments: indicates the maximum of the sum of the number of namespaces attached to each I/O controller in the Domain. yes, it's a sum — read it twice bestie 🧮
  • maxcna — Maximum I/O Controller Namespace Attachments: indicates the maximum number of namespaces that are allowed to be attached to this I/O controller.
  • oaqd — Optimal Aggregated Queue Depth: indicates the recommended maximum total number of outstanding I/O commands across all I/O queues on the controller for optimal operation 🌟 (recommended, bestie, not enforced — it's a vibe check, not a rule)
  • rhiri — Recommended Host-Initiated Refresh Interval (RHIRI). If the Host-Initiated Refresh capability is supported, then this field indicates the recommended time interval in days from last power down to the time at which the host should initiate the Host-Initiated Refresh operation. If this field is cleared to 0h, then this field is not reported.
  • hirt — Host-Initiated Refresh Time (HIRT). If the Host-Initiated Refresh capability is supported, then this field indicates the nominal amount of time in minutes that the controller takes to complete the Host-Initiated Refresh operation. If this field is cleared to 0h, then this field is not reported. ✨
  • cmmrtd — Controller Maximum Memory Range Tracking Descriptors: indicates the maximum number of Memory Range Tracking Descriptors the controller supports 🔍
  • nmmrtd — NVM Subsystem Maximum Memory Range Tracking Descriptors: indicates the maximum number of Memory Range Tracking Descriptors the NVM subsystem supports. subsystem-wide edition 💅
  • minmrtg — Minimum Memory Range Tracking Granularity: indicates the minimum value supported in the Requested Memory Range Tracking Granularity (RMRTG) field of the Track Memory Ranges data structure.
  • maxmrtg — Maximum Memory Range Tracking Granularity: indicates the maximum value supported in the Requested Memory Range Tracking Granularity (RMRTG) field of the Track Memory Ranges data structure. min's twin, max's moment 👑
  • trattr — Tracking Attributes: indicates supported attributes for the Track Send command and Track Receive command. see enum nvme_id_ctrl_trattr 🎀
  • rsvd577 — Reserved 💀
  • mcudmq — Maximum Controller User Data Migration Queues: indicates the maximum number of User Data Migration Queues supported by the controller.
  • mnsudmq — Maximum NVM Subsystem User Data Migration Queues: indicates the maximum number of User Data Migration Queues supported by the NVM subsystem 🌈
  • mcmr — Maximum CDQ Memory Ranges: indicates the maximum number of memory ranges allowed to be specified by the PRP1 field of a Controller Data Queue command.
  • nmcmr — NVM Subsystem Maximum CDQ Memory Ranges: indicates the maximum number of memory ranges for all Controller Data Queues in the NVM subsystem.
  • mcdqpc — Maximum Controller Data Queue PRP Count: indicates the maximum number of PRPs allowed to be specified in the PRP list in the Controller Data Queue command 🧮
  • rsvd588 — Reserved 💀
  • subnqn — NVM Subsystem NVMe Qualified Name. UTF-8 null terminated string 🌸 (yes, it's a string, null terminated, iconic)
  • rsvd1024 — Reserved 💀
  • ioccsz — I/O Queue Command Capsule Supported Size: defines the maximum I/O command capsule size in 16 byte units 📦
  • iorcsz — I/O Queue Response Capsule Supported Size: defines the maximum I/O response capsule size in 16 byte units 📦
  • icdoff — In Capsule Data Offset: defines the offset where data starts within a capsule. This value is applicable to I/O Queues only 🫶
  • fcatt — Fabrics Controller Attributes. see enum nvme_id_ctrl_fcatt.
  • msdbd — Maximum SGL Data Block Descriptors: indicates the maximum number of SGL Data Block or Keyed SGL Data Block descriptors that a host is allowed to place in a capsule. A value of 0h indicates no limit 🔥 (0h = go wild, bestie)
  • ofcs — Optional Fabric Commands Support. see enum nvme_id_ctrl_ofcs.
  • dctype — Discovery Controller Type (DCTYPE). This field indicates what type of Discovery controller the controller is (see enum nvme_id_ctrl_dctype) 🦋
  • rsvd1807 — Reserved 💀
  • psd — Power State Descriptors. see struct nvme_id_psd ⚡
  • vs — Vendor Specific ✨

and that's the whole member list, bestie — we made it 🎉 this page lives in the struct nvme_id_ctrl chapter of libnvme(2), stamped July 2026. go forth and read your controller registers, mwah 💖👑

📦 where this page comes from