nvme_get_feature_length2(2)

💖 nvme_get_feature_length2 — a libnvme API moment 💖

okay bestie, welcome to nvme_get_feature_length2(2), a lil libnvme API function that is genuinely so useful once it clicks. no cap. 🎀

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✨ NAME ✨

nvme_get_feature_length2 — retreive the command payload length for a specific feature identifier

(yes, that says "retreive", we're keeping it exactly as it is, it's iconic, we don't touch it 💅)

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✨ SYNOPSIS ✨

int nvme_get_feature_length2 (int fid , __u32 cdw11 , enum nvme_data_tfr dir , __u32 *len );

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✨ ARGUMENTS ✨

so here's the whole cast of characters, and every single one matters 🫶

• fid — the feature identifier. peek at enum nvme_features_id for the full roster of who's who. ✨
• cdw11 — this value may affect the transfer. lowkey only one known fid cares about it, and that's NVME_FEAT_FID_HOST_ID. 👑
• dir — data transfer direction, and it's giving bool energy: false means host to controller, true means controller to host. it may affect the transfer, and again there's only one known fid in on this, which is NVME_FEAT_FID_HOST_MEM_BUF. 🌈
• len — on success, this gets set to this feature's payload length in bytes. that's the whole prize bestie. 💖

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✨ RETURN ✨

• 0 on success 🎉
• -1 with errno set to EINVAL if the function did not recognize fid 😭

fr fr, if you're getting EINVAL, it's not a you problem, it's a "that fid is not a thing I know" problem. check your feature identifier. 💀

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🦋 a lil sign-off 🦋

this page is straight from the libnvme API manual, July 2026 edition — that's the source and the date, both accounted for, and she ate. go get that payload length bestie 💅✨💖