Dear Benjamin, dear Paul, dear Michael, with commit 48b545b8018d ("powerpc/microwatt: Use standard 16550 UART for console"), you have some code in arch/powerpc/kernel/udbg_16550.c, conditional on the Kconfig symbol PPC_EARLY_DEBUG_MICROWATT. However, since then, the definition of this Kconfig symbol was never introduced to the mainline repository or current linux-next, nor am I finding any pending patch for that. Are you going to add this config definition soon? Or did you identify that this setup code in udbg_16550.c is not actually needed and can we simply drop this code again? This issue was identified with the script ./scripts/checkkconfigsymbols.py. Best regards, Lukas