mtd_ooblayo...nt_freebytes(9)

✨ mtd_ooblayo...nt_freebytes(9) ✨

okay so bestie, welcome to the Kernel API Manual 💅 this one's a lil function with a big name — the header calls it mtd_ooblayo...nt_freebytes(9) but its actual government name (per the NAME section, iykyk) is mtd_ooblayout_count_freebytes. yes she got truncated in the header. it's giving main character with a long name energy 🎀

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🌸 NAME 🌸

mtd_ooblayout_count_freebytes — literally just counts the number of free bytes in OOB 🦋

like. that's it. that's her job. no cap.

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⭐ SYNOPSIS ⭐

int mtd_ooblayout_count_freebytes (struct mtd_info *mtd );

bestie look at that signature, it's so clean 🫶

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💖 ARGUMENTS 💖

• mtd — the mtd info structure 💫 (yes that's the whole description, she's lowkey mysterious)

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👑 DESCRIPTION 👑

so here's the tea: this function works exactly like mtd_ooblayout_count_bytes, except — wait for it — it counts free bytes. that's the plot twist. iconic. 🔥

it returns zero on success, and a negative error code otherwise. so if you get 0 back, slay, you ate 💅 if you get something negative, that's your sign to go touch some grass and go debug 🙈

ngl, don't ignore a negative return here — that's the error code, not a vibe. 😭

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🌈 SEE ALSO 🌈

she does not exist in a vacuum, bestie, she's part of a whole friend group 🫶 all of these:

• the kernel file ./drivers/mtd/mtdcore.c — that's where she lives 🏠
• mtd_wunit_to_pairing_info(9)
• mtd_pairing_info_to_wunit(9)
• mtd_pairing_groups(9)
• add_mtd_device(9)
• del_mtd_device(9)
• mtd_device_parse_register(9)
• mtd_device_unregister(9)
• register_mtd_user(9)
• unregister_mtd_user(9)
• get_mtd_device(9)
• of_get_mtd_device_by_node(9)
• get_mtd_device_nm(9)
• mtd_ooblayout_ecc(9)
• mtd_ooblayout_free(9)
• mtd_ooblayout_find_region(9)
• mtd_ooblayout_find_eccregion(9)
• mtd_ooblayout_get_bytes(9)
• mtd_ooblayout_set_bytes(9)
• mtd_ooblayout_count_bytes(9)
• mtd_ooblayout_get_eccbytes(9)
• mtd_ooblayout_set_eccbytes(9)
• mtd_ooblayout_get_databytes(9)
• mtd_ooblayout_set_databytes(9)
• mtd_ooblayout_count_eccbytes(9)
• mtd_kmalloc_up_to(9)

like, that's the whole group chat right there 🧚✨ read them all, periodt.

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and that's the page, bestie!! 🎀 this whole thing lives in ./drivers/mtd (the Kernel API Manual, obvi), and it's dated October 2026 — so yes, she's from the future, we love a forward-thinking icon 💜 bye bestie, go count those free bytes! 🌸