Internal storage and removable media (POWER-FINAL-08)

Layout

p8 used to be the stock firmware's runtime FAT storage. The eMMC write guard now includes its exact span (stock logical sector 3742720 to the end of the exposed disk, directly after Y2DATA). Boot areas, CACHE, protected/NVRAM partitions and the hidden tail remain unwritable.

What the owner sees

• MTP Internal Storage is /media/internal/music (fixed slot, storage id 0xffff0001); SD Card is /media/sd.

  The old /data/music folder is no longer exported.

• Reborn follows the platform's record: Y2Media when /run/y2/internal-media.json says Ready for this boot and this

  mount, /data/music before that (an unprovisioned device keeps working).

• Factory reset does not erase Y2Media music; delete files over MTP.

User guide: Storage.

Device result (Beta 7.9, owner's player, 2026-10-17): p8 restored to the stock FAT from the 2026-10-10 backup; on the first restart after the confirmed update the setup ran in ≈16 s (case 2), Y2MEDIA identical to the original (label, UUID, start/size, features, 358 336 inodes, 1 432 576 blocks), 509 files in Old Player Files hash-identical, 3 leftovers dropped; on the update's health boot it reported Pending/update_in_progress.

Automatic setup (Beta 7.9)

S02y2-media runs y2-platform internal-media setup --automatic before USB and Reborn. It acts only on the stock FAT at the exact p8 geometry, after the read-only check (issue #44 rules), from a read-only mount at /run/y2/old-storage:

• nothing but leftovers (empty folders, thumbnail caches, computer clutter) → format at once;
• user files ≤ 400 MB with ≥ 150 MB left on Y2DATA → copied to /data/system/internal-media-kept with SHA-256,

  format, moved to music/Old Player Files with SHA-256 (then /data/music as before);

• more, or unreadable → Waiting: nothing changes, the old storage stays mounted read-only and is exported over MTP

  as Old Storage; Reborn asks once, Settings → Storage → Set Up Internal Storage runs internal-media setup --confirm-shown (the serial this boot reported) and erases it, then the player restarts.

/data/system/internal-media-setup.json (phase staging → formatting → migrating) makes every step resumable; only that record allows formatting a p8 that an interrupted format left unreadable. Skipped (Pending) while an update waits for its health check, below 3.70 V on battery, or with an unknown battery. The filesystem is created with every setting named (internal_media.MKFS), identical to the first Y2MEDIA. This boot's result: /run/y2/internal-media-setup.json and storage.internal_setup in y2-platform status. Start screen phases media_setup*.

Commands (root, over USB SSH)

y2-platform internal-media status
y2-platform internal-media mount | unmount
y2-platform internal-media provision --confirm-serial 3F93-07E6 [--no-migrate]
y2-media status                      # shows partition_bytes and capacity_state (Undersized) for the card
y2-media format --confirm-cid <CID>  # repartition the whole card, ext4 label Y2SD; names the card
y2-media grow                        # e2fsck + resize2fs for an undersized ext4 card

provision replaces only the stock FAT filesystem whose serial you pass, refuses a mounted or any other filesystem, creates ext4 Y2MEDIA, mounts it, copies /data/music across with SHA-256 verification and removes an original only after every file verified. Re-running it resumes a partial migration and never overwrites a differing file. Nothing formats or deletes automatically. The file-level backup of the stock partition taken before this change is out/deep-sleep-final/evidence/20261010/93-stock-fat-partition-backup/.

Known limits

• Format and grow are explicit owner operations; a card with a foreign or undersized filesystem is only reported.
• An ext4 card is not readable by a PC when pulled out; MTP is the transfer path. exFAT remains mountable.
• No endurance measurement of ext4 on this eMMC; no physical power-loss test of Y2Media yet.
• No physical power cut during the automatic setup yet (resume is host-tested at every phase); case 3 (large old library,

  Old Storage, Set Up Now) is host-tested only.

• ext4's background inode-table initialisation asks the eMMC for WRITE_ZEROES inside p8 at start; the eMMC write guard

  refuses erase-class commands (mmc_erase: group start error -30, one I/O error line). Harmless (unused inodes are tracked by the group descriptors), but log noise to clean up (allow zeroing inside p8, or format without lazy init).

• Going back to stock leaves p8 as ext4, which stock Android cannot read; it has to format it (untested).
• MTP keeps 96 MiB and 128 inodes free per storage (tools/usb/mtp-safe.c); uploads are PIO-bound at ≈9–10 MB/s

  (receive DMA plan).