ERROR: RSB: set run-time address: 0x10003: meaning

On an Allwinner H616 or H618 board with an AXP313a PMIC, TF-A BL31 will print:

ERROR: RSB: set run-time address: 0x10003

This is non-fatal. The board continues to boot normally into U-Boot and Linux. It appears on essentially every H616/H618 boot that uses the AXP313a PMIC.

What's happening: RSB (Reduced Serial Bus) is Allwinner's proprietary two-wire bus for talking to the PMIC. The BL31 stage tries to set a run-time RSB address for the PMIC and gets back error code 0x10003 from the RSB layer. The exact semantic decode of 0x10003 isn't documented in mainline TF-A comments; behaviorally it's an RSB-layer failure setting the run-time address for the PMIC on this class of chip.

Why it's harmless: U-Boot SPL already brought up the PMIC over RSB successfully earlier in boot (that's how DRAM training happened at all). BL31's attempt to redo the address programming is a no-op on the AXP313a and the sunxi TF-A code correctly treats the failure as non-fatal.

When to worry: you should NOT see this on H6 or A64 boards (those use AXP805/AXP803 and RSB init should succeed at BL31). Seeing it on those SoCs means U-Boot SPL didn't bring the PMIC up properly and you have a real problem.