Add bitbox03-boot0

### .cargo/config.toml
@@ -1,2 +1,18 @@
 # Include host-specific Cargo settings generated by scripts/bootstrap-cargo-config.
 include = [{ path = "config.local.toml", optional = true }]
+
+[build]
+# Use our own copy of libsecp256k1-zpk instead of the one bundled with secp256k1-sys, also in `cargo
+# test` and other cargo-based builds. This is replicated in src/CMakeLists.txt,
+# test/simulator-graphical*/CMakeLists.txt for CMake-based builds.
+# See https://github.com/rust-bitcoin/rust-secp256k1/tree/7c8270a8506e31731e540fab7ee1abde1f48314e/secp256k1-sys#linking-to-external-symbols
+rustflags = ["--cfg", "rust_secp_no_symbol_renaming"]
+
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+rustflags = [
+    "--cfg", "rust_secp_no_symbol_renaming",
+    "-C", "linker-plugin-lto",
+    # This is needed if your flash or ram addresses are not aligned to 0x10000 in memory.x
+    # See https://github.com/rust-embedded/cortex-m-quickstart/pull/95
+    "-C", "link-arg=--nmagic",
+]

### .github/workflows/ci-common.yml
@@ -210,6 +210,7 @@ jobs:
           - firmware-blupgrade-bitbox02-btconly-development
           - factory-setup
           - firmware-debug
+          - bitbox03-boot0
           - simulator
           - simulator-graphical
           - simulator-graphical-bb03
@@ -241,7 +242,15 @@ jobs:
         run: ./.ci/check-unwanted-symbols
 
       - name: Print hashes
-        run: sha256sum build*/bin/*
+        run: |
+          {
+            for dir in build*/bin src/rust/target/thumbv8m.main-none-eabihf/debug; do
+              if [ -d "$dir" ]; then
+                find "$dir" -maxdepth 1 -type f -print0
+              fi
+            done
+            true
+          } | xargs -0 -r sha256sum
 
       - name: Upload artifact
         if: github.event_name == 'push' && !cancelled()
@@ -253,6 +262,7 @@ jobs:
             build*/bin/*.elf
             build*/bin/*.map
             build*/bin/simulator*
+            src/rust/target/thumbv8m.main-none-eabihf/debug/bitbox03-*
 
   # Build simulators for macos aarch64
   build-macos:

### Makefile
@@ -258,3 +258,17 @@ clean:
 # When you vendor rust libs avoid duplicates
 vendor-rust-deps:
 	./external/vendor-rust.sh
+
+# It is important that cargo is executed from `src/rust` so that it loads the
+# configuration for the vendored dependencies.
+bitbox03-boot0:
+	(cd src/rust; cargo bitbox03-boot0-stm32u5a9j-dk)
+	arm-none-eabi-size src/rust/target/thumbv8m.main-none-eabihf/debug/bitbox03-boot0
+	arm-none-eabi-size -Ax src/rust/target/thumbv8m.main-none-eabihf/debug/bitbox03-boot0
+bitbox03-boot0-release:
+	(cd src/rust; cargo bitbox03-boot0-stm32u5a9j-dk-release)
+	arm-none-eabi-size src/rust/target/thumbv8m.main-none-eabihf/release/bitbox03-boot0
+	arm-none-eabi-size -Ax src/rust/target/thumbv8m.main-none-eabihf/release/bitbox03-boot0
+
+flash-bitbox03-boot0-openocd:
+	./scripts/flash-bitbox03-boot0-openocd.sh

### scripts/flash-bitbox03-boot0-openocd.sh
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+image="${1:-$repo_root/src/rust/target/thumbv8m.main-none-eabihf/debug/bitbox03-boot0}"
+config="$repo_root/scripts/stm32u5a9j-dk.cfg"
+
+if [[ ! -f "$image" ]]; then
+    echo "image not found: $image" >&2
+    exit 1
+fi
+
+exec openocd \
+    -f "$config" \
+    -c "program \"$image\" verify reset exit"

### scripts/stm32u5.gdb
@@ -0,0 +1,22 @@
+# Helper function to start RTT server in openocd. Remember to let the firmware
+# run until RTT channels have been initialized before running this command.
+# Sets up channel 0 in/out for terminals and channel 1 for API requests/responses
+define rtt_start
+    monitor rtt setup 0x20000200 0x1000
+    monitor rtt start
+    monitor rtt server start 19021 0
+    monitor rtt server start 19022 1
+end
+
+define r
+    monitor reset halt
+end
+
+target extended-remote :3333
+
+monitor reset init
+
+load
+
+# Step into first instruction
+si

### scripts/stm32u5a9j-dk.cfg
@@ -0,0 +1,16 @@
+source [find interface/stlink.cfg]
+
+transport select swd
+
+reset_config srst_only connect_assert_srst
+#reset_config none
+
+source [find target/stm32u5x.cfg]
+
+cortex_m reset_config sysresetreq
+
+# set working area beyond the RTT buffers so they don't get clobbered
+set _TARGETNAME [target current]
+$_TARGETNAME configure -work-area-phys 0x20002000
+
+adapter speed 3300

### src/CMakeLists.txt
@@ -260,6 +260,7 @@ if(NOT CMAKE_CROSSCOMPILING)
         ${CARGO} clippy
           $<$<BOOL:${CMAKE_VERBOSE_MAKEFILE}>:-v>
           --all-features
+          --workspace
           --manifest-path ${CMAKE_CURRENT_SOURCE_DIR}/rust/Cargo.toml
           --target-dir ${RUST_BINARY_DIR}/clippy
           --release

### src/rust/.cargo/config.toml
@@ -21,9 +21,6 @@ replace-with = "vendored-sources"
 [source.vendored-sources]
 directory = "../../external/vendor"
 
-[build]
-# Use our own copy of libsecp256k1-zpk instead of the one bundled with secp256k1-sys, also in `cargo
-# test` and other cargo-based builds. This is replicated in src/CMakeLists.txt,
-# test/simulator-graphical*/CMakeLists.txt for CMake-based builds.
-# See https://github.com/rust-bitcoin/rust-secp256k1/tree/7c8270a8506e31731e540fab7ee1abde1f48314e/secp256k1-sys#linking-to-external-symbols
-rustflags = ["--cfg", "rust_secp_no_symbol_renaming"]
+[alias]
+bitbox03-boot0-stm32u5a9j-dk = "build -p bitbox03-boot0 --target=thumbv8m.main-none-eabihf --features board-stm32u5a9j-dk,rtt"
+bitbox03-boot0-stm32u5a9j-dk-release = "build -p bitbox03-boot0 --target=thumbv8m.main-none-eabihf --release --features board-stm32u5a9j-dk"

### src/rust/Cargo.lock
@@ -460,6 +460,18 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "bitbox03-boot0"
+version = "0.1.0"
+dependencies = [
+ "bitbox-board-stm32u5a9j-dk",
+ "bitbox-boot-utils",
+ "bitbox-debug",
+ "bitbox-platform-stm32u5",
+ "cortex-m-rt",
+ "log",
+]
+
 [[package]]
 name = "bitcoin"
 version = "0.32.7"

### src/rust/Cargo.toml
@@ -4,6 +4,7 @@
 
 members = [
     "async_test",
+    "bins/bitbox03-boot0",
     "bitbox-aes",
     "bitbox-board-stm32u5a9j-dk",
     "bitbox-board-stm32u5a9j-dk-build",

### src/rust/bins/bitbox03-boot0/Cargo.toml
@@ -0,0 +1,22 @@
+[package]
+name = "bitbox03-boot0"
+version = "0.1.0"
+edition = "2024"
+
+[[bin]]
+name = "bitbox03-boot0"
+path = "src/main.rs"
+test = false
+bench = false
+
+[features]
+board-stm32u5a9j-dk = ["dep:bitbox-board-stm32u5a9j-dk"]
+rtt = ["bitbox-debug/rtt"]
+
+[dependencies]
+bitbox-boot-utils = { path = "../../bitbox-boot-utils" }
+bitbox-board-stm32u5a9j-dk = { path = "../../bitbox-board-stm32u5a9j-dk", optional = true }
+bitbox-platform-stm32u5 = { path = "../../bitbox-platform-stm32u5" }
+bitbox-debug = { path = "../../bitbox-debug" }
+cortex-m-rt = "0.7"
+log = { version = "0.4.22", default-features = false }

### src/rust/bins/bitbox03-boot0/bitbox03-boot0.ld
@@ -0,0 +1,6 @@
+INCLUDE memory.x
+REGION_ALIAS("FLASH", BOOT0_FLASH);
+
+PROVIDE(_image_payload_start = ORIGIN(BOOT0_FLASH));
+
+INCLUDE bitbox03-common.ld

### src/rust/bins/bitbox03-boot0/build.rs
@@ -0,0 +1,26 @@
+use std::path::PathBuf;
+
+fn main() {
+    if !cfg!(feature = "board-stm32u5a9j-dk") {
+        panic!("select a BitBox03 board feature, e.g. `board-stm32u5a9j-dk`")
+    }
+
+    let target = std::env::var("TARGET").expect("TARGET not set");
+    if target.starts_with("thumb") {
+        let manifest_dir =
+            PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR not set"));
+        let out_dir = PathBuf::from(std::env::var("OUT_DIR").expect("OUT_DIR not set"));
+
+        let lds_from = manifest_dir.join("bitbox03-boot0.ld");
+        let lds_to = out_dir.join("bitbox03-boot0.ld");
+        println!("cargo::rerun-if-changed={}", lds_from.display());
+        std::fs::copy(lds_from, &lds_to).expect("copy linker script");
+
+        println!("cargo::rustc-link-search={}", out_dir.display());
+        println!(
+            "cargo::rustc-link-arg=-Map={}",
+            out_dir.join("bitbox03-boot0.map").display()
+        );
+        println!("cargo::rustc-link-arg=-Tbitbox03-boot0.ld");
+    }
+}

### src/rust/bins/bitbox03-boot0/src/main.rs
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#![no_std]
+#![no_main]
+
+#[cfg(feature = "board-stm32u5a9j-dk")]
+use bitbox_board_stm32u5a9j_dk as board;
+use bitbox_boot_utils::{IMAGE_HEADER_MAGIC_BOOT1, bootload, halt, vector_table_from_image_header};
+use core::panic::PanicInfo;
+use cortex_m_rt::entry;
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    log::error!("{info}");
+    halt();
+}
+
+fn boot1_vector_table() -> Result<*const u32, ()> {
+    // SAFETY: The board memory layout defines BOOT1_ADDR as an aligned,
+    // readable flash slot of BOOT1_MAX_LEN bytes. Boot0 does not mutate it
+    // while validating the image.
+    unsafe {
+        vector_table_from_image_header(
+            board::memory::BOOT1_ADDR,
+            board::memory::BOOT1_MAX_LEN,
+            board::memory::RAM_ADDR,
+            board::memory::RAM_LEN,
+            IMAGE_HEADER_MAGIC_BOOT1,
+        )
+    }
+}
+
+#[entry]
+fn main() -> ! {
+    bitbox_debug::rtt_logger_init!();
+    log::debug!("init");
+
+    let vector_table = match boot1_vector_table() {
+        Ok(vector_table) => vector_table,
+        Err(()) => {
+            log::error!("halt: boot1 image is invalid");
+            halt();
+        }
+    };
+    // SAFETY: Boot0 deliberately trusts boot1 at the fixed slot after checking
+    // its image header and vector table, including the stack pointer and reset
+    // vector ranges.
+    unsafe { bootload(vector_table) }
+}