mediatek-optical

The protocol of MediaTek MT1959 and MT1939 optical drives (BD/DVD): command encoding, identity decoding, memory-read and flash sequences over any SCSI transport, chip detection, the AES-CMAC integrity table, and reconstruction of the flashable OEM image from a drive read.

[dependencies]
mediatek-optical = { version = "0.5", features = ["drive"] }

Module	Feature	Contents
`cdb`	—	CDB constructors and field constants
`Identity`	—	Decoded INQUIRY, boot banner and identity descriptor; `chip()`
`Chip`	—	`Mt1959` / `Mt1939`, from an identity tag or banner
`layout`	—	2 MiB image geometry; boot page, boot mirror, drive-written regions
`sense`	—	Sense parsing; flash-fault and no-medium classification
`drive`	`drive`	`Transport` trait; `identify`, `read_memory`, `feature`, `enter_update` → `Session`
`image`	`image`	`detect_chip`, `is_uhd`, `is_drive_read`; `cmac` verify / resign
`enc`	`enc`	AES-128-ECB transport envelope
`oem`	`oem`	`rebuild` with `Catalog`, `Factory`, `content_key`, `Provenance`

The default build and the drive feature are no_std and allocation-free. image and oem use std.

Drive memory

READ BUFFER mode 6 exposes the 2 MiB flash at file offsets with two differences from the image that was flashed:

The boot page 0x0..0x400 reads back as the image's page at 0x10000. Flash stores the boot page in a form that never reads back.
The drive rewrites four regions at runtime and an update never overwrites them: the UHD and BD host revocation lists, the settings page and the calibration block (layout::DRIVE_WRITTEN).

Across 205 OEM update images of both generations (LG, HP and ASUS), 204 store the same boot page, and every drive-read difference falls in those five ranges. oem::content_key hashes everything else, so a drive read and the OEM image it came from share a key.

OEM reconstruction

oem::rebuild turns a complete drive read into a flashable image:

Exact: the read's content key matches a cataloged OEM build. The result is byte-identical to that vendor file.
Chip default: an unknown build (a revision the catalog lacks, or a modified image) gets its chip generation's default factory contents. Regions the drive left erased stay erased. The result carries no per-unit data but is a reconstruction, reported as such in Provenance.

A boot page that is neither the stored page nor the mirror of a drive read is refused: no image is produced whose stored boot page is unknown. The crate ships no catalog; build one from OEM images with oem::Factory::from_image and oem::content_key.

Example

use mediatek_optical::{cdb, drive};

struct Sg(/* your pass-through */);

impl drive::Transport for Sg {
    type Error = std::io::Error;
    fn exec(&mut self, cdb: &[u8], data: drive::Data<'_>) -> Result<usize, Self::Error> {
        /* issue `cdb`; fill or send `data` */
    }
    fn sense(&self) -> Option<(u8, u8, u8)> { /* last sense */ }
}

let id = drive::identify(&mut t)?;
let chip = id.chip().expect("not an MT19xx drive");
let mut session = drive::enter_update(&mut t)?;
for (i, chunk) in image.chunks(cdb::CHUNK).enumerate() {
    session.write((i * cdb::CHUNK) as u32, chunk)?;
}
session.finish()?;

Command set

Flash-sequence CDBs are 12 bytes, exactly as the OEM update tool issues them. Offsets are 24-bit big-endian.

Command	Constructor	CDB
Memory read	`cdb::read_memory(off, len)`	`3C 06 00 <off> <len> 00`
Identity / feature	`cdb::inquiry(n)`, `cdb::get_configuration(code, n)`	`12 …`, `46 02 <code> …`
Probe	`cdb::probe()`	`3C 06 00 1E C0 00 00 01 00 00 00 00`
Ready	`cdb::test_unit_ready()`	`00 × 12`
Enter update	`cdb::enter_update()`	`3B 01 00 00 00 00 00 00 00 0B 00 00`
Write chunk	`cdb::transfer(off, len)`	`3B 06 00 <off> 00 <len16> 00 00 00`
Commit	`cdb::finish()`	`3B 07 00 00 00 00 00 00 00 00 1B 12`
Status	`cdb::request_sense()`	`03 00 00 10 80 00 00 00 00 00 00 00`

The drive erases and programs flash when the last chunk of a complete 2 MiB image lands. The commit is a trailing handshake.

Safety

An update session writes drive firmware. A wrong image, or an interrupted session, can leave the drive unusable. Verify an image with image::cmac before flashing. The identity, feature and memory-read commands are read-only.

Minimum supported Rust version

1.75.

License

MIT. See LICENSE-MIT.

mediatek-optical 0.5.0