ubi_compare_lebs(9)

💅 ubi_compare_lebs — like, the kernel API manual, but make it make sense

okay so bestie, today we're learning about ubi_compare_lebs from the kernel API manual. yes it's a mouthful, no you're not gonna be weird about it. it's literally just "which of these two eraseblocks is the newer one" energy and honestly? iconic. 🦋

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✨ NAME ✨

ubi_compare_lebs — find out which logical eraseblock is newer.

like a vibe check but for LEBs. no cap.

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🌸 SYNOPSIS 🌸

int ubi_compare_lebs (struct ubi_device *ubi , const struct ubi_ainf_peb
*aeb , int pnum , const struct ubi_vid_hdr *vid_hdr );

that's the whole signature, copy it exactly, don't @ me 💅

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🎀 ARGUMENTS 🎀

• ubi — the UBI device description object. it's giving "the whole situation" energy.
• aeb — the first logical eraseblock you wanna compare. this one's the struct ubi_ainf_peb baddie.
• pnum — the physical eraseblock number of the second logical eraseblock in this little showdown.
• vid_hdr — the volume identifier header of that second logical eraseblock. yes it's const, yes it's slaying.

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🧚 DESCRIPTION 🧚

okay so here's the tea: this function compares 2 copies of a LEB and tells you which one is newer. periodt.

If it works? you get a positive value back. If it fails? negative error code, sadly. 😭

Now the success return codes are giving bitmask realness, so let's break it down bit by bit, iykyk:

• bit 0 cleared — the first PEB (the one described by aeb) is newer than the second PEB (the one described by pnum and vid_hdr).
• bit 0 set — the second PEB is the newer one. she's fresh. ✨
• bit 1 cleared — no bit-flips were detected in the newer LEB. clean. flawless. no notes.
• bit 1 set — bit-flips were detected in the newer LEB. uh oh 💀
• bit 2 cleared — the older LEB is not corrupted. okay she's fine.
• bit 2 set — the older LEB is corrupted. not fine. sending thoughts and prayers 🫶

fr fr, read those bits carefully — bit 0 is the "who's newer" bit, bit 1 is the "the newer one has bit-flips" bit, and bit 2 is the "the older one is corrupted" bit. don't mix them up, bestie.

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👑 SEE ALSO 👑

if you liked this one, you're gonna love the rest of the lineup. these all live in 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), add_fastmap(9), validate_vid_hdr(9), add_volume(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)

that's the whole squad, go say hi 🌈

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and that's the page, bestie! 🎀 this one comes to you from ./drivers/mtd/ubi, dated October 2026 — go off, you absolutely ate. 💖🔥