add_fastmap(9)

💅 add_fastmap — kernel API manual, but make it make sense

okay so bestie, this one lives in the add_fastmap(9) section of the Kernel API Manual, and it's genuinely not that deep once you see it. let me put you on. 🫶

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✨ NAME ✨

add_fastmap — adds a Fastmap related physical eraseblock. that's it. that's the whole vibe. one job, does it, slays. 💅

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✨ SYNOPSIS ✨

int add_fastmap (struct ubi_attach_info *ai , int pnum , struct
ubi_vid_hdr *vid_hdr , int ec );

like, four things go in, an int comes out. classic. 🎀

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✨ ARGUMENTS ✨

• ai — the attaching information. literally the whole context of the attach we're doing rn. main character energy. 👑
• pnum — the physical eraseblock number that the VID header came from. we're keeping receipts on where it came from fr fr.
• vid_hdr — the volume identifier header. yes queen, the VID header. 💜
• ec — the erase counter of the physical eraseblock. gotta know how cooked it is. 🔥

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✨ DESCRIPTION ✨

so what this function does is: it allocates a struct ubi_ainf_peb object for a Fastmap physical eraseblock pnum, and then it adds it to the fastmap list. periodt. 🌸

and which blocks end up in that list? honestly both kinds, bestie: Fastmap super blocks and Fastmap data blocks — and they can come from either the most recent Fastmap we're attaching from, or from old Fastmaps. and those old ones? yeah, they're gonna get erased. 💀 not us being dramatic, that's just what happens to them.

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🌈 SEE ALSO 🌈

the whole friend group, all tagged (9), all from the Kernel file ./drivers/mtd/ubi/attach.c:

• find_or_add_av(9)
• ubi_find_or_add_av(9)
• ubi_alloc_aeb(9)
• ubi_free_aeb(9)
• add_to_list(9)
• add_corrupted(9)
• validate_vid_hdr(9)
• add_volume(9)
• ubi_compare_lebs(9)
• ubi_add_to_av(9)
• ubi_add_av(9)
• ubi_find_av(9)
• ubi_remove_av(9)
• early_erase_peb(9)
• ubi_early_get_peb(9)
• check_corruption(9)
• scan_peb(9)
• late_analysis(9)
• destroy_av(9)
• destroy_ai(9)
• scan_all(9)
• scan_fast(9)
• ubi_attach(9)
• self_check_ai(9)

no cap, if you're deep in UBI attach code, you're gonna meet every single one of these. it's giving family reunion. 🙈

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and that's the page, bestie — brought to you by ./drivers/mtd/ubi, stamped October 2026, living under the Kernel API Manual umbrella, filed under add_fastmap(9). go forth and attach. 🦋✨