CXL-WRITE-LABELS(1)

💾 CXL-WRITE-LABELS(1) — the cxl manual, but make it make sense 🎀

okay bestie so you've found yourself in the cxl manual pages and this one is literally the label-writing one. sit down, grab a strawberry drink 🍓, and let's get into it — you're gonna slay this.

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✨ NAME ✨

cxl-write-labels — write data to the label area on a memdev

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🌸 SYNOPSIS 🌸

cxl write-labels <mem> [-i <filename>]

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🦋 DESCRIPTION 🦋

so. the region label area is this small persistent partition of capacity that exists on some CXL memory devices — not all of them, okay, just some, don't come for me. and what's it for? it's used to configure, or to figure out, the set of memory devices that are participating in different interleave sets. very main character of it honestly.

what this command does is read data from the input filename — or from stdin, if you're feeling spontaneous — and write it to the given <mem> device. simple! iconic!

but 👑 here's the vibe check that matters: the device must not be active in any region, and it must not be actively registered with the nvdimm subsystem. because if it is? the kernel will literally not allow write access to that device's label data area. like, it will shut you down, no cap. so check first, bestie, fr fr.

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💅 OPTIONS 💅

• <memory device(s)> — a memX device name, or a memdev id number. use it to restrict the operation to the specified memdev(s). and if you want zero restrictions at all, you can pass the keyword all — that's you saying "no thanks, I don't want any restriction" 🫶
• -S, --serial — instead of reading the argument(s) as a memdev id number, interpret <memdev> as a list of serial numbers. iykyk, different vibe entirely.
• -s, --size= — limit the operation to the given number of bytes. and a size of 0? that means operate over the entire label capacity. the whole thing. go off.
• -O, --offset= — begin the operation at the given offset into the label area. like starting mid-song 🎵
• -v — turns on verbose debug messages in the library. caveat though: this only works if libcxl was built with logging and debug enabled. so if it's quiet, it's not you, it's the build 🙈
• -b, --bus= — restrict the operation to the specified bus. keep it scoped, keep it cute.
• -i, --input — input file. that's the file it reads the data from (or stdin, remember 🌈).

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🔥 SEE ALSO 🔥

cxl-read-labels(1), cxl-zero-labels(1), CXL-2.0 9.13.2

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⚠️ real talk one more time: if the device is active in a region or registered with the nvdimm subsystem, the kernel is not letting you write to its label data area. that's not a suggestion, that's the rule 💀

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okay that's the whole page, you ate that 💖 this was cxl manual, version/date 2026-06-30 — go forth and write those labels, bestie, you've got this ✨🎀🧚