firmware: mirror fw 0.8.3 RESET ABI — RESET_TO_DEFAULTS (0x01) + reset_to_defaults(), true-OEM/marker-gated docs

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [1.7.3] — UNRELEASED
+
+### Changed
+
+- firmware: mirror the fw 0.8.3 RESET ABI — added `RESET_TO_DEFAULTS` (`0x01`, restore the baked create-time defaults into RAM) and `FirmwareControl::reset_to_defaults()`; `RESET_TO_OEM` (`0xFF`) is now documented as TRUE OEM (RAM passthrough **and** the NV block blanked to all-`0xFF`, so the drive is traceless), and `RESET_TO_FLASH` as marker-gated (a never-saved drive loads the defaults). Wire values unchanged.
+
 ## [1.7.2] — UNRELEASED
 
 ### Fixed

src/firmware/mod.rs

@@ -31,7 +31,9 @@
 //!
 //! Every feature defaults to [`STATE_PASSTHROUGH`] (firmware does not touch the
 //! subsystem → byte-identical to OEM); [`Verb::Reset`] with [`RESET_TO_OEM`]
-//! returns every feature to passthrough, while [`RESET_TO_FLASH`] reloads the last
+//! returns every feature to passthrough (and, firmware ≥0.8.3, blanks the NV block
+//! so the drive is traceless), [`RESET_TO_DEFAULTS`] restores the baked create-time
+//! defaults, while [`RESET_TO_FLASH`] reloads the last
 //! [`Verb::Save`]d config block.
 
 use crate::scsi::{DataDirection, ScsiTransport};
@@ -114,11 +116,21 @@ pub const REGION_FREE: u8 = 0x0F;
 
 /// [`Verb::Reset`] mode (rides in the state slot `cdb[6]`): reload the saved flash
 /// config block into the RAM feature-state table, discarding un-saved RAM changes
-/// — the non-destructive "revert to last SAVE".
+/// — the non-destructive "revert to last SAVE". Marker-gated in firmware ≥0.8.3: a
+/// never-saved drive loads the baked create-time defaults instead.
 pub const RESET_TO_FLASH: u8 = 0x00;
 
-/// [`Verb::Reset`] mode (rides in the state slot `cdb[6]`): force every feature to
-/// [`STATE_PASSTHROUGH`] (OEM behaviour everywhere), regardless of the saved config.
+/// [`Verb::Reset`] mode (rides in the state slot `cdb[6]`): restore the baked
+/// per-create **defaults** (the create-time flags, e.g. UHD/BD on) into the RAM
+/// feature-state table. RAM-only — does not touch flash. This is what a never-saved
+/// drive boots to. Firmware ≥0.8.3.
+pub const RESET_TO_DEFAULTS: u8 = 0x01;
+
+/// [`Verb::Reset`] mode (rides in the state slot `cdb[6]`): TRUE OEM. Forces every
+/// feature to [`STATE_PASSTHROUGH`] in RAM **and** (firmware ≥0.8.3) writes the NV
+/// config block all-`0xFF` — marker included — so the drive is byte-for-byte like a
+/// never-saved/never-configured drive (no trace it was ever set). Because the marker
+/// is then `0xFF`, the NEXT boot loads the baked defaults, exactly like a fresh drive.
 pub const RESET_TO_OEM: u8 = 0xFF;
 
 /// The verb selector in `cdb[4]`. These numeric values ARE the wire protocol.
@@ -133,8 +145,10 @@ pub enum Verb {
     Get = 0x03,
     /// Restore the RAM feature-state table. The mode rides in `cdb[6]` (the state
     /// slot): [`RESET_TO_FLASH`] (`0x00`) reloads the saved flash config block back
-    /// into RAM (discarding un-saved changes), [`RESET_TO_OEM`] (`0xFF`) forces every
-    /// feature to [`STATE_PASSTHROUGH`] (out-of-the-box behaviour). Ignores feature.
+    /// into RAM (discarding un-saved changes; marker-gated in fw ≥0.8.3),
+    /// [`RESET_TO_DEFAULTS`] (`0x01`) restores the baked create-time defaults, and
+    /// [`RESET_TO_OEM`] (`0xFF`) forces every feature to [`STATE_PASSTHROUGH`] AND
+    /// blanks the NV block (traceless, fw ≥0.8.3). Ignores feature.
     Reset = 0x04,
     /// Diagnostic RAM peek: [`MEMREAD_LEN`] bytes at the 32-bit address in
     /// `cdb[5..9]` (big-endian).
@@ -267,8 +281,9 @@ pub fn build_get_cdb(feature: Feature) -> [u8; CDB_LEN] {
 
 /// Build a `RESET` CDB. `mode` rides in the state slot (`cdb[6]`):
 /// [`RESET_TO_FLASH`] (`0x00`) reloads the saved flash config into RAM,
-/// [`RESET_TO_OEM`] (`0xFF`) forces every feature to passthrough. Floors its
-/// data-in at [`MIN_ALLOC_LEN`] for the same HW min-transfer reason as
+/// [`RESET_TO_DEFAULTS`] (`0x01`) restores the baked create-time defaults, and
+/// [`RESET_TO_OEM`] (`0xFF`) forces every feature to passthrough (and blanks NV).
+/// Floors its data-in at [`MIN_ALLOC_LEN`] for the same HW min-transfer reason as
 /// [`build_set_cdb`].
 pub fn build_reset_cdb(mode: u8) -> [u8; CDB_LEN] {
     build_cdb(Verb::Reset, None, Some(mode), MIN_ALLOC_LEN)
@@ -528,14 +543,24 @@ impl<'a> FirmwareControl<'a> {
         self.exec_in(&cdb).map(|_| ())
     }
 
-    /// Restore every feature to [`STATE_PASSTHROUGH`] (RESET with
-    /// [`RESET_TO_OEM`]). Data-in phase for the same reason as [`set`](Self::set) —
-    /// a no-data RESET is aborted.
+    /// Restore every feature to [`STATE_PASSTHROUGH`] (RESET with [`RESET_TO_OEM`])
+    /// — TRUE OEM: firmware ≥0.8.3 also blanks the NV block so the drive is
+    /// traceless. Data-in phase for the same reason as [`set`](Self::set) — a no-data
+    /// RESET is aborted.
     pub fn reset(&mut self) -> Result<()> {
         let cdb = build_reset_cdb(RESET_TO_OEM);
         self.exec_in(&cdb).map(|_| ())
     }
 
+    /// Restore the baked create-time defaults into the RAM feature-state table
+    /// (RESET with [`RESET_TO_DEFAULTS`]) — what a never-saved drive boots to; does
+    /// not touch flash. Firmware ≥0.8.3. Data-in phase for the same reason as
+    /// [`reset`](Self::reset).
+    pub fn reset_to_defaults(&mut self) -> Result<()> {
+        let cdb = build_reset_cdb(RESET_TO_DEFAULTS);
+        self.exec_in(&cdb).map(|_| ())
+    }
+
     /// Reload the saved flash config block back into the RAM feature-state table
     /// (RESET with [`RESET_TO_FLASH`]), discarding any un-saved RAM changes — the
     /// non-destructive "revert to last SAVE". Data-in phase for the same reason as

src/firmware/mod_tests.rs

@@ -44,6 +44,7 @@ fn state_and_frame_constants_match_abi() {
     assert_eq!(REGION_DVD_BASE, 0x00);
     assert_eq!(REGION_FREE, 0x0F);
     assert_eq!(RESET_TO_FLASH, 0x00);
+    assert_eq!(RESET_TO_DEFAULTS, 0x01);
     assert_eq!(RESET_TO_OEM, 0xFF);
 }
 
@@ -332,6 +333,16 @@ fn reset_sends_reset_cdb_and_clears_state() {
     assert_eq!(m.states, FeatureStates::all_passthrough());
 }
 
+#[test]
+fn reset_to_defaults_sends_the_defaults_mode_cdb() {
+    let mut m = FwMock::new();
+    {
+        let mut fw = FirmwareControl::new(&mut m);
+        fw.reset_to_defaults().expect("reset to defaults");
+    }
+    assert_eq!(m.cdbs[0], build_reset_cdb(RESET_TO_DEFAULTS));
+}
+
 #[test]
 fn save_then_reset_to_flash_restores_the_saved_value() {
     // SET a feature, SAVE it, force all-passthrough with RESET(to-OEM), then