nvmf_reg_read64(9)

📦 version 7.3.1, in nixpkgs unstable

💅 nvmf_reg_read64 — the Kernel API Manual, bestie edition

Okay so real talk, we're in the nvmf_reg_read64(9) girlies' section of the kernel docs today, and honestly? She's iconic. Let's get into it. 🦋

✨ NAME ✨

nvmf_reg_read64 — the NVMe Fabrics "Property Get" API function. That's it, that's the whole vibe. 🎀

🌸 SYNOPSIS 🌸

int nvmf_reg_read64 (struct nvme_ctrl *ctrl , u32 off , u64 *val );

like, that's the whole signature. three params. no cap. 💅

🫶 ARGUMENTS 🫶

  • ctrl — the Host NVMe controller instance. she's the one maintaining the admin queue, and that queue is literally what gets used to submit the property read command over to the allocated controller resource on the target system. main character energy tbh 👑
  • off — the starting offset value of the targeted property register (peep the fabrics section of the NVMe standard, iykyk). this is where you're reading from, bestie ✨
  • val — the OUTPUT parameter 🫶. after a successful read, this is gonna contain the value of the property. she holds the answer. treasure her 🙈

🦋 DESCRIPTION 🦋

So the host system uses this to retrieve a 64-bit capsule property value from an NVMe controller on the target system. That's the mission. That's what we're doing here. ⭐

And before you ask — "capsule property" is literally a "PCIe register concept" that got applied to the NVMe fabrics space. so like, it's a concept that migrated. she's versatile. 💀✨

🔥 RETURN 🔥

the return values, laid out and slaying:

  • 0 — successful read 🎉
  • > 0 — NVMe error status code 😭
  • < 0 — Linux errno error code 💀

like fr fr, check your return value. it's giving "important." 🌈

🌸 SEE ALSO 🌸

Kernel file ./drivers/nvme/host/fabrics.c — go read her, she's the source material 🧚

and the whole friend group:

go say hi to all of them. they're all so valid. 💜

okay that's the whole page bestie, go read a 64-bit property off a controller and slay 💅✨

mwah 💋 — this little love letter lives in ./drivers/nvme/host, dated October 2026, and it's still nvmf_reg_read64(9) at heart. see you in the group chat 🎀🦋💖

📦 where this page comes from