ubi_scan_fastmap(9)

✨ ubi_scan_fastmap 💅

okay so this is a manual page from the Kernel API Manual for ubi_scan_fastmap(9) — yes bestie, the fastmap scanner, we're getting into it 🫶

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🌸 SYNOPSIS 🌸

int ubi_scan_fastmap (struct ubi_device *ubi , struct ubi_attach_info
*ai , struct ubi_attach_info *scan_ai );

like literally that's the whole signature, no notes, copying it exactly because that's how we do 💖

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🎀 ARGUMENTS 🎀

• ubi — the UBI device object 💅 this is the main character of the operation
• ai — the UBI attach info that's gonna get filled — think of it as the empty notebook you're handing over ✨
• scan_ai — the UBI attach info coming from the first 64 PEBs 🧚 this one's got a job: it's used to find the most recent Fastmap data structure, iykyk

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🦋 DESCRIPTION 🦋

okay so the returns, pay attention bestie, this is the whole vibe check 📋

• Returns 0 on success — slay, we ate 👑
• Returns UBI_NO_FASTMAP if no fastmap was found — like, nothing there, empty, a whole ghost town 💀
• Returns UBI_BAD_FASTMAP if one was found but it's not usable — found it but it's giving expired milk 😭
• < 0 indicates an internal error — that's a "not me, that's a system problem" moment 🙈

ngl the returns are the entire point here, lowkey highkey memorize them 💜

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🌈 SEE ALSO 🌈

the whole friend group 🫶 first up, the kernel file itself:

• Kernel file ./drivers/mtd/ubi/fastmap.c

and then the crew, in exactly this order, no cap:

• init_seen(9), free_seen(9), set_seen(9), self_check_seen(9), ubi_calc_fm_size(9), new_fm_vbuf(9), add_aeb(9), add_vol(9), assign_aeb_to_av(9), update_vol(9), process_pool_aeb(9), unmap_peb(9), scan_pool(9), count_fastmap_pebs(9), ubi_attach_fastmap(9), find_fm_anchor(9), ubi_write_fastmap(9), invalidate_fastmap(9), return_fm_pebs(9), ubi_update_fastmap(9)

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and that's the page!! 🎀 sign-off time: this one lives in ./drivers/mtd/ubi, dated October 2026, and it's filed under ubi_scan_fastmap(9) — periodt 💅✨🦋