On Fri, 29 Apr 2022, Niklas Schnelle wrote: > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends > not being declared. We thus need to add HAS_IOPORT as dependency for > those drivers using them. [...] > diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig > index cd93ea6eed65..e216bf745e78 100644 > --- a/drivers/tty/serial/8250/Kconfig > +++ b/drivers/tty/serial/8250/Kconfig > @@ -6,7 +6,7 @@ > > config SERIAL_8250 > tristate "8250/16550 and compatible serial support" > - depends on !S390 > + depends on HAS_IOPORT > select SERIAL_CORE > select SERIAL_MCTRL_GPIO if GPIOLIB > help Similarly here some 8250-compatible platform or PCI/e serial port devices use MMIO, e.g.: serial8250.0: ttyS2 at MMIO 0x1f000900 (irq = 20, base_baud = 230400) is a 16550A or: 0001:01:00.0: ttyS0 at MMIO 0x600c080401000 (irq = 40, base_baud = 15625000) is a 16C950/954 so this has to be sorted out within the driver rather than by disabling it altogether. Possibly with a suitable conditional wired to HAS_IOPORT in `set_io_from_upio' in drivers/tty/serial/8250/8250_port.c. Maciej