Execute SWI 0x00 through original ARM code. Read the restart flag before clearing 512 bytes of BIOS work RAM, reset System/SVC/IRQ stacks and specified registers, then branch to ROM or EWRAM in ARM System mode.
Keep device state and clocks active, preserve unrelated CPU banks, and document the deterministic IRQ-masked restart status. Add eleven tests for every flag byte, ARM/Thumb and User/System callers, exact memory bounds, bank state, restart execution, DMA/timers, and unsupported exception callers.
Validated on Darwin arm64: 705 default and 694 core-only tests in debug and release; formatting, Clippy, rustdoc, ten native window smoke tests, and CPU/timer demos pass.
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