boot: boot_serial: add raw (non-console) SMP recovery protocol#4
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Pull request overview
Adds a build-time-selectable raw SMP transport (BOOT_SERIAL_RAW_PROTOCOL) to mcuboot's serial recovery, mirroring Zephyr's CONFIG_UART_MCUMGR_RAW_PROTOCOL. In raw mode the SMP header + payload is exchanged as plain binary (no base64, length prefix, CRC16, NLIP framing or \n); packet boundaries come from the SMP header nh_len. The console encoding remains the default; the two modes are mutually exclusive and the base64/CRC libraries are dropped in raw mode.
Changes:
- New raw TX path in
boot_serial_outputplus aboot_serial_input_rawreassembler that drains complete packets and keeps residue, with the legacy console decode path#ifdef-gated. serial_adapter.cgains a binary-safe ISR path (no\nsplit, end-of-IRQ fragment flush) and aconsole_read_rawreader that retains an unconsumed fragment tail across calls.- New
BOOT_SERIAL_RAW_PROTOCOLKconfig (conditionallyselects BASE64/CRC),CONFIG_→MCUBOOT_SERIAL_RAW_PROTOCOLmapping, aserial_recovery_raw.confsample, plus docs and a release note.
Reviewed changes
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Show a summary per file
| File | Description |
|---|---|
| boot/boot_serial/src/boot_serial.c | Raw TX in boot_serial_output; gates console decode; adds boot_serial_input_raw and raw branch in the read loop. |
| boot/zephyr/serial_adapter.c | Binary-safe ISR fragment delivery and console_read_raw with persistent pending-tail. |
| boot/zephyr/Kconfig.serial_recovery | Adds BOOT_SERIAL_RAW_PROTOCOL; makes BASE64/CRC conditional. |
| boot/zephyr/include/mcuboot_config/mcuboot_config.h | Maps CONFIG_BOOT_SERIAL_RAW_PROTOCOL to MCUBOOT_SERIAL_RAW_PROTOCOL. |
| boot/zephyr/serial_recovery_raw.conf | Sample Kconfig fragment for raw mode. |
| docs/serial_recovery.md | Documents the new transport encoding option. |
| docs/release-notes.d/serial-recovery-raw-protocol.md | Release note for the new option. |
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A few cleanups to make the diff better
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Add the BOOT_SERIAL_RAW_PROTOCOL option, which exchanges SMP packets over the serial port as raw binary instead of the SMP-over-console encoding: no base64, no two-byte length prefix, no CRC16 and no SHELL_NLIP framing. Packet boundaries are derived from the length field of the SMP header, so the encoding is transport-agnostic (UART, CDC ACM, CAN, ...) and only requires a binary-capable link. The mcumgr client must be configured to use a matching raw transport. This mirrors Zephyr's CONFIG_UART_MCUMGR_RAW_PROTOCOL. The two encodings are mutually exclusive and selected at build time; in raw mode the base64 and CRC code and libraries are dropped, saving roughly 1 KiB of flash and 1 KiB of RAM and increasing transfer speed. Because the raw encoding has no CRC or framing to detect a truncated packet, also add BOOT_SERIAL_RAW_PROTOCOL_INPUT_TIMEOUT (enabled by default with the raw protocol): a partially received packet is dropped after BOOT_SERIAL_RAW_PROTOCOL_INPUT_TIMEOUT_MS without new data so a stalled transfer cannot wedge recovery. This mirrors Zephyr's CONFIG_MCUMGR_TRANSPORT_RAW_UART_INPUT_TIMEOUT. A serial_recovery_raw.conf fragment and a matching Twister build test (sample.bootloader.mcuboot.serial_recovery_raw) are added so the raw configuration is built in CI. Signed-off-by: JP Hutchins <jp@intercreate.io> Assisted-By: Claude:opus-4.8
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Summary
Adds raw (non-console) SMP support to mcuboot serial recovery (the bootloader-side SMP server), mirroring Zephyr's
CONFIG_UART_MCUMGR_RAW_PROTOCOLso the same raw mcumgr client can talk to both the application and the bootloader.With
BOOT_SERIAL_RAW_PROTOCOL, the SMP packet (nmgr_hdr+ payload) is exchanged as plain binary instead of the SMP over console encoding — no base64, no two-byte length prefix, no CRC16, noSHELL_NLIPframing, no\n. Packet boundaries are derived from the length field of the SMP header, so the encoding is transport-agnostic (UART, CDC ACM, CAN, RTT, …) and only needs a binary-capable link. The two encodings are mutually exclusive and selected at build time; in raw mode the base64 and CRC code and libraries are dropped.Because raw framing has no CRC or delimiter to detect a truncated packet,
BOOT_SERIAL_RAW_PROTOCOL_INPUT_TIMEOUT(enabled by default with the raw protocol;…_INPUT_TIMEOUT_MSdefault3000) discards a partially received packet after a period without new data so a stalled or malformed transfer cannot permanently wedge recovery — mirroring Zephyr'sCONFIG_MCUMGR_TRANSPORT_RAW_UART_INPUT_TIMEOUT.Changes
boot_serial.c— raw TX inboot_serial_output; console-onlyboot_serial_in_dec/dec_buf#ifdef'd out in raw mode; newboot_serial_input_raw()that drains every complete packet from the receive buffer (by SMP-header length) and preserves the residue; input-expiration timeout inboot_serial_read_console.serial_adapter.c—#ifdef-gated raw paths; binary-safe byte collection (no\nsplit);console_read_raw()retains an unconsumed fragment tail across calls instead of truncating.Kconfig.serial_recovery—BOOT_SERIAL_RAW_PROTOCOLplus…_INPUT_TIMEOUT/…_INPUT_TIMEOUT_MS;BASE64/CRCselected only for the console encoding.mcuboot_config.h—CONFIG_→MCUBOOT_*macro mappings.sample.yaml—sample.bootloader.mcuboot.serial_recovery_rawTwister entry so the raw config is built in CI.serial_recovery.md+ release note;serial_recovery_raw.confsample fragment.Verification
Built for
nrf52840dk/nrf52840(Zephyr 4.4.0, SDK 0.17.4,-Werror -Wall -Wextra) across the config matrix — raw (timeout on / off), raw +WAIT_FOR_DFU, and console — all compile clean and link:#ifdef-out, zero cost when off).Reviewed across multiple passes; fixes applied for multi-packet residue handling, the
boot_serial_outputraw guard, and a fragment-truncation data-loss path.Note: this is build-verified. Functional client↔server transfer testing belongs upstream in Zephyr
tests/boot/with_mcumgr/, alongside where the mirrored Zephyr PR added its owntransport_raw_uarttest.🤖 Generated with Claude Code