STRUCT UBI_ATTACH_INFO(9)

💖 struct ubi_attach_info(9) 💖

okay bestie, so this is a page from the Kernel API Manual, and it's literally all about struct ubi_attach_info — the MTD device attaching information. yes, the whole vibe is "we just attached an MTD device, here's everything we learned." slay.

✨ SYNOPSIS ✨

struct ubi_attach_info {
    struct rb_root volumes;
    struct list_head corr;
    struct list_head free;
    struct list_head erase;
    struct list_head alien;
    struct list_head fastmap;
    int corr_peb_count;
    int empty_peb_count;
    int alien_peb_count;
    int bad_peb_count;
    int maybe_bad_peb_count;
    int vols_found;
    int highest_vol_id;
    int is_empty;
    int force_full_scan;
    int min_ec;
    int max_ec;
    unsigned long long max_sqnum;
    int mean_ec;
    uint64_t ec_sum;
    int ec_count;
    struct kmem_cache *aeb_slab_cache;
    struct ubi_ec_hdr *ech;
    struct ubi_vid_io_buf *vidb;
 };

🎀 Members 🎀

okay so here's the cast of characters, one by one, no skips:

• volumes — the root of the volume RB-tree, the main character of the tree world 🌳
• corr — list of corrupted physical eraseblocks 😭
• free — list of free physical eraseblocks ✨
• erase — list of physical eraseblocks which have to be erased 🧹
• alien — list of physical eraseblocks which should not be used by UBI (e.g., those belonging to "preserve"-compatible internal volumes) 👽
• fastmap — list of physical eraseblocks which relate to fastmap (e.g., eraseblocks of the current and not yet erased old fastmap blocks) 🗺️
• corr_peb_count — count of PEBs in the corr list 🧮
• empty_peb_count — count of PEBs which are presumably empty (contain only 0xFF bytes) 🫧
• alien_peb_count — count of PEBs in the alien list 👽
• bad_peb_count — count of bad physical eraseblocks 💀
• maybe_bad_peb_count — count of bad physical eraseblocks which are not marked as bad yet, but which look like bad 🙈
• vols_found — number of volumes found 🔍
• highest_vol_id — highest volume ID 👑
• is_empty — flag indicating whether the MTD device is empty or not 🪹
• force_full_scan — flag indicating whether we need to do a full scan and drop
• min_ec — lowest erase counter value 📉
• max_ec — highest erase counter value 📈
• max_sqnum — highest sequence number value 🔢
• mean_ec — mean erase counter value ⚖️
• ec_sum — a temporary variable used when calculating mean_ec 🧾
• ec_count — a temporary variable used when calculating mean_ec 🧾
• aeb_slab_cache — slab cache for struct ubi_ainf_peb objects 🧺
• ech — temporary EC header. Only available during scan ⏳
• vidb — listed right there in the struct, bestie 🫶

ngl, that struct has a lot of fields. it's giving "I contain multitudes" energy 💅

🌈 Description 🌈

so what does it actually do? This data structure contains the result of attaching an MTD device, and it may be used by other UBI sub-systems to build final UBI data structures, further error-recovery and so on. literally the receipts of an attach, kept around so the rest of UBI can do its thing ✨

🦋 SEE ALSO 🦋

Kernel file ./drivers/mtd/ubi/ubi.h:struct ubi_vid_io_buf(9), struct ubi_wl_entry(9), struct ubi_ltree_entry(9), struct ubi_rename_entry(9), struct ubi_fastmap_layout(9), struct ubi_fm_pool(9), struct ubi_eba_leb_desc(9), struct ubi_volume(9), struct ubi_volume_desc(9), struct ubi_debug_info(9), struct ubi_device(9), struct ubi_ainf_peb(9), struct ubi_ainf_volume(9), struct ubi_work(9), ubi_init_vid_buf(9), ubi_free_vid_buf(9), ubi_get_vid_hdr(9), ubi_ro_mode(9), vol_id2idx(9), idx2vol_id(9), ubi_is_fm_vol(9), ubi_find_fm_block(9)

and that's the whole page, bestie 🫶 it lives over in ./drivers/mtd/ubi and this edition is dated October 2026 — go off, kernel docs, periodt 💅✨