The previous implementation was a bare tail-jump to tinygo_scanstack
without spilling any registers or passing an sp argument. On Xtensa
windowed ABI, heap pointers held in physical registers were invisible
to the conservative GC, causing it to collect live objects and leading
to nil pointer dereferences under allocation pressure.
Flush all register windows to the stack using recursive call4 (15
levels for NAREG=64), then pass the current sp to tinygo_scanstack so
the GC scan from sp to stackTop covers every live value. Interrupts
are briefly masked during the spill to prevent window-overflow
exceptions from interfering.
Fixes crashes on ESP32-S3 observed when serving concurrent HTTP
requests.
Signed-off-by: deadprogram <ron@hybridgroup.com>
Extend the linker script with proper IROM/DROM section layout for flash
execute-in-place. Update the boot assembly MMU init to dynamically map
all required flash pages based on _irom_end/_drom_end symbols instead
of hardcoding a single page.
Signed-off-by: deadprogram <ron@hybridgroup.com>
The ESP32-S3 ROM bootloader loads IRAM/DRAM into SRAM but does not
configure the flash cache or MMU. Previously the target incorrectly
reused the ESP32 boot assembly (esp32.S) which lacks flash XIP support.
Add a dedicated esp32s3.S boot assembly that:
- Sets up windowed-ABI registers, stack, and FPU
- Disables all watchdog timers (RTC, TIMG0, TIMG1, Super WDT)
- Configures VECBASE and clears PS.EXCM before any callx4
- Calls ROM functions to configure cache modes:
rom_config_instruction_cache_mode (16KB, 8-way, 32B line)
rom_config_data_cache_mode (32KB, 8-way, 32B line)
- Initializes MMU, maps flash page 0 for IROM and DROM,
clears bus-shut bits, and enables both caches
- Jumps to runtime.main in IROM (flash)
Update the linker script (esp32s3.ld) to place .text and .rodata in
flash-mapped regions (IROM/DROM) with proper alignment for the MMU
page size. Update esp32s3-interrupts.S with proper exception vector
handlers. Point esp32s3.json at the new esp32s3.S instead of esp32.S.
Signed-off-by: deadprogram <ron@hybridgroup.com>
deadprogram