Add wolfBoot HAL port for RealTek RTL8735B (AmebaPro2)#797
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Pull request overview
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Adds initial wolfBoot HAL enablement for the RealTek RTL8735B (AmebaPro2) platform, including build integration and packaging support for producing a flashable image using the vendor SDK tooling.
Changes:
- Introduces a new RTL8735B HAL implementation and linker script for SRAM-staged boot.
- Adds an SDK shim header to avoid pulling FreeRTOS/CMSIS-OS into the wolfBoot build.
- Adds build system wiring (arch.mk), example config, and a packaging script to generate
flash_ntz.bin.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| tools/scripts/amebapro2_package.sh | Adds packaging flow to convert wolfboot.elf into a vendor-style flash image. |
| hal/rtl8735b/sdk-shim/cmsis_os.h | Provides CMSIS-OS opaque typedefs to compile SDK headers without FreeRTOS. |
| hal/rtl8735b/README | Documents the RTL8735B HAL design, backends, and SDK integration approach. |
| hal/rtl8735b.ld | Defines SRAM layout, RAM start-table placement, and partition symbols. |
| hal/rtl8735b.c | Implements RTL8735B HAL + RAM start-table/trampoline + SDK-backed ext flash/cache hooks. |
| config/examples/rtl8735b.config | Provides an example configuration for RTL8735B builds and partition layout. |
| arch.mk | Adds TARGET=rtl8735b build integration and SDK include/define wiring. |
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| # Compile all objects. The default link of wolfboot.elf is expected to fail here | ||
| # (unresolved SDK/ROM symbols); capture the object list from its [LD] line. | ||
| make TARGET=rtl8735b 2>/tmp/rtl8735b_make_err.txt \ | ||
| | grep -A1 '\[LD\] wolfboot.elf' | tail -1 > /tmp/rtl8735b_objs.txt || true | ||
| OBJS="$(cat /tmp/rtl8735b_objs.txt)" | ||
| if ! echo "$OBJS" | grep -q 'hal/rtl8735b.o'; then | ||
| echo "error: object compile failed (no hal/rtl8735b.o in link line). make stderr:" >&2 | ||
| tail -8 /tmp/rtl8735b_make_err.txt >&2 | ||
| exit 1 | ||
| fi |
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| # Make the ROM symbol table visible to the linker. | ||
| grep -q 'romsym_is.so' config/target.ld || \ | ||
| sed -i '1i INCLUDE "romsym_is.so"' config/target.ld | ||
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| "$CC" -mcpu=cortex-m33 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=softfp \ | ||
| -ffreestanding -nostartfiles --specs=nosys.specs \ | ||
| -T config/target.ld \ | ||
| -L "$SDKREL/ROM/GCC" -L "$SDKREL/application/output" \ | ||
| $OBJS \ |
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| # Override via environment: | ||
| # AMEBA_SDK RealTek ameba-rtos-pro2 checkout | ||
| # ASDK_PATH ASDK 10.3.0 toolchain bin dir | ||
| # OUTDIR work/output dir (default /tmp/wolfboot_amebapro2_pkg) | ||
| set -e | ||
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| WOLFBOOT_ELF="${1:-wolfboot.elf}" | ||
| AMEBA_SDK="${AMEBA_SDK:-$HOME/GitHub/ameba-rtos-pro2}" | ||
| ASDK_PATH="${ASDK_PATH:-$HOME/ameba-pro2-workspace/asdk/asdk-10.3.0/linux/newlib/bin}" | ||
| OUTDIR="${OUTDIR:-/tmp/wolfboot_amebapro2_pkg}" |
| tools/scripts/amebapro2_package.sh wolfboot.elf | ||
| ``` | ||
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| For the default `sdk` backend, `make TARGET=rtl8735b` compiles every wolfBoot object (including the RealTek SDK driver chain folded into `hal/rtl8735b.o`), but the final `wolfboot.elf` link must resolve the SDK SoC libraries (`liboutsrc.a`, `libsoc_ntz.a`) and the ROM symbol table (`romsym_is.so`), which live in the SDK build tree. `tools/scripts/rtl8735b_build.sh` runs that compile-then-SDK-resolved-link, and `tools/scripts/amebapro2_package.sh` then packages wolfBoot (in `PT_FW1`) with the RealTek partition table, boot, and certs via `elf2bin` into `flash_ntz.bin`. Both honor `AMEBA_SDK`/`ASDK_PATH`. See `hal/rtl8735b/README`. |
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Adds wolfBoot support for the RealTek RTL8735B (Arm Cortex-M33) as used on the AmebaPro2 EVB. wolfBoot runs as a second-stage verified bootloader and A/B firmware-update engine on top of RealTek's secure-boot ROM -- the non-TrustZone "Model A" integration.
How it boots
RealTek ROM -> boot.bin -> wolfBoot (staged into SRAM via a RealTek RAM start-table) -> verifies the application in external SPI NOR (ECDSA P-256 / SHA-256), applies any pending A/B update, copies the verified image into DDR, and jumps. This reuses wolfBoot's existing RAMBOOT path (
EXT_FLASH+NO_XIP,src/update_ram.c); no new boot assembly is required.What's included
hal/rtl8735b.c/hal/rtl8735b.ld: single-file HAL -- HAL entry points,ext_flash_*over the RealTek SPI NOR, the RAM start-table + trampoline, cache maintenance, a self-containedDEBUG_UARTconsole, and a reset-reason readout. Flash/UART/cache backend selected byHAL_BACKEND(sdk= default/working;bare= scaffold).config/examples/rtl8735b.configand anarch.mktarget block.tools/scripts/rtl8735b_build.sh(compile + SDK-resolved final link) andtools/scripts/amebapro2_package.sh(wrapwolfboot.elfinto a flashableflash_ntz.bin).hal/rtl8735b/test-app/: a minimal DDR test application (also demonstrates servicing the vendor watchdog).docs/Targets.mdsection (build, staging an app, A/B update, watchdog, status/roadmap) andhal/rtl8735b/README.Verified on the AmebaPro2 EVB
DEBUG_UARTconsole and signed boot of an application from the BOOT partition (verify -> copy to DDR -> jump).Follow-ons (not in this PR)
See the "Status and roadmap" list in the
docs/Targets.mdsection: device-bound encrypted updates bound to the Hardware Unique Key (wolfSSL PR #10677), TrustZone-M "Model B", the no-SDK "bare" backend, and measured boot / DICE.