7.29.10. Nodebox v3 (nbxv3) CPU Module

The Nodebox v3 (nbxv3) is a COM-HPC Server CPU module built on the NXP LX2160A (16x Cortex-A72) for baremetal 100GE packet processing with Class C clock management for telecom applications.

The platform port lives entirely under plat/nxp/soc-lx2160a/nbxv3/ and reuses the shared LX2160A SoC layer. Board-specific behaviour is kept out of the common soc.c through plat_soc_early_init_hook() and the weak board hooks.

7.29.10.1. Boot source

Production boot is FlexSPI NOR only (GigaDevice GD55LB02GF, 256 MiB xSPI NOR, JEDEC C8 60 1C). The console is UART1 at 0x021C0000, 115200 8N1, no flow control. SD / eMMC are not wired.

7.29.10.2. Two BL2 variants

A single source tree produces two BL2 images, selected at build time by NBXV3_BL2_BOOTSTRAP:

Production XIP BL2 (default, NBXV3_BL2_BOOTSTRAP=0): .text / .rodata execute in place from the FlexSPI NOR AHB window, embedded in the PBL at NOR offset 0x9000. .data / .bss / stack live in OCRAM. XIP avoids the LX2160A multi-bit-ECC trap on uninitialised OCRAM during the Service Processor’s Block-Copy.
Bootstrap BL2 (NBXV3_BL2_BOOTSTRAP=1): OCRAM-resident, non-XIP. Loaded into OCRAM by a JTAG probe (OpenOCD) while the SoC runs the ROM-fallback RCW; used only for first-time / recovery NOR provisioning.

7.29.10.3. Unified runtime flash bootstrap

Both factory-fresh and provisioned boards run the same BL2. The mode is decided at runtime by reading DCFG_RCWSR0.MEM_PLL_RAT: a value below the DDR4-1600 DLL-lock minimum (16) means the Service Processor fell back to a ROM hard-coded RCW, so the NOR is blank or corrupt and provisioning is required. Otherwise the production RCW is live and BL2 proceeds normally.

power-on / reset
       |
       v
+-------------------------+
| Service Processor loads |
| RCW from NOR (or ROM    |
| fallback if NOR blank)  |
+-------------------------+
       |
       v
BL2: plat_soc_early_init_hook()
read DCFG_RCWSR0.MEM_PLL_RAT
       |
       +-----------------------------< MEM_PLL_RAT >= 16 >----------------+
       |                                (production RCW live)             |
       | MEM_PLL_RAT < 16                                                 |
       | (ROM fallback: NOR blank/corrupt)                                |
       v                                                                  v
====== BOOTSTRAP MODE (JTAG semihosting) ======            ====== PRODUCTION MODE ======
open flash_manifest.json over ARM semihosting               bootstrap returns silently
       |                                                            |
       v                                                            v
for each manifest region:                                   DDR init (SPD over I2C)
  - erase NOR slot                                                  |
  - stream file from JTAG host -> NOR                               v
  - SHA-256 verify via NOR AHB window                        load FIP (BL31 + BL33)
       |                                                            |
       v                                                            v
SW_RST_REQ  ->  true POR                                     hand off to BL31 in DRAM
       |
       +--> board reboots; SP now loads the freshly
            written production RCW -> PRODUCTION MODE

The provisioning set is data-driven by flash_manifest.json (resolved over the JTAG probe’s semihosting stdio), not by C code. The manifest can stage just the boot ROM’s RCW (PBL), or a full set: PBL + FIP + DDR-FIP + U-Boot + kernel + ramdisk. Smaller manifests provision faster over the JTAG semihosting link. The schema is documented in plat/nxp/soc-lx2160a/nbxv3/MANIFEST.md.

7.29.10.4. RCW build stamp (PBL -> BL2)

The RCW carries no version which prevents the software identification. On this board, this identification is set into one of the LX2160A DCFG general-purpose scratch registers, SCRATCHRW13.

The PBI command block embedded in the PBL writes it while the boot Service Processor processes the RCW, and the DCFG SCRATCHRW registers survive the hand-off to BL2 (they are cleared only by a power-on reset).

The 32-bit word is packed, all-BCD:

 31   28 27   24 23   16 15    8 7     0
+-------+-------+-------+-------+-------+
|CARRIER|  TAG  |  YY   |  MM   |  DD   |   all BCD
+-------+-------+-------+-------+-------+

CARRIER identifies the carrier board the CPU module is plugged into.
TAG is a fixed marker, 0xB
YY / MM / DD are the RCW build date in BCD

The first boot lines based on the RCW shall be some of the following:

NOTICE  Iliad nbxv32 RCW v.20260820
NOTICE  Iliad nbxv3 (bring-up, no IO) RCW v.20260820

This pairs with the MEM_PLL_RAT probe: that register tells BL2 whether a production RCW is live, while SCRATCHRW13 tells it which one, and on which carrier.

7.29.10.5. Board policy deviations from the LX2160A reference boards

SMMU bypass is always on. There is no untrusted DMA path on this product; the bypass is a performance decision for the DPAA2 / WRIOP packet path. Reference boards only bypass under secure boot.
POVDD strapped to ground. TA_PROG_SFP is not software-controllable, so in-system fuse provisioning is not supported; fuses are burned by an external jig.
Verbose EA / SError handler dumps ESR / FAR / ELR / SPSR_EL3 for kernel bring-up forensics.
Optional features enabled in the board makefile: NXP_DDR_DUAL_DIMM_TOLERANT (tolerant SPD compare for two-lot DIMM pairing) and NXP_XSPI_DIAG (FlexSPI JEDEC / SFDP / SR1 probe helpers used by the bootstrap and bring-up diagnostics).

7.29.10.6. Building

The fip_ddr target packs the Synopsys DDR PHY training firmware. Get it using a NXP clone of ddr-phy-binary repository into the TF-A root so the default DDR_PHY_BIN_PATH (./ddr-phy-binary/lx2160a) resolves:

git clone https://github.com/NXP/ddr-phy-binary

Production XIP BL2 + FIP (embedded in the PBL at NOR offset 0x9000):

make PLAT=nbxv3 BOOT_MODE=flexspi_nor RCW=$RCW_BIN BL33=$UBOOT_BIN \
     pbl fip fip_ddr

Bootstrap BL2 (build, loaded by OpenOCD into OCRAM, resolves staged images over ARM semihosting):

make PLAT=nbxv3 NBXV3_BL2_BOOTSTRAP=1 BOOT_MODE=semihosting bl2

SUPPORTED_BOOT_MODE is flexspi_nor semihosting.