Hello, I'm working on an x86 system that doesn't have any legacy UARTs (0x3f8, etc) mapped. Instead it uses MMIO UARTs defined by ACPI. It seems that in this case the univ8250_console console is registered too early. It replaces `earlycon` before the ACPI consoles have had a chance to load. This results in losing about 500ms of console logs in my case. Here is my log with some print statements: ``` [ 0.677076] serial8250_isa_init_ports: start [ 0.681808] serial8250_isa_init_ports: checking old serial port 0 [ 0.688566] serial8250_isa_init_ports: iobase: 0x3f8, irq: 4, uartclk: 1843200 [ 0.696579] serial8250_isa_init_ports: checking old serial port 1 [ 0.703338] serial8250_isa_init_ports: iobase: 0x2f8, irq: 3, uartclk: 1843200 [ 0.711352] serial8250_isa_init_ports: checking old serial port 2 [ 0.718110] serial8250_isa_init_ports: iobase: 0x3e8, irq: 4, uartclk: 1843200 [ 0.726124] serial8250_isa_init_ports: checking old serial port 3 [ 0.732884] serial8250_isa_init_ports: iobase: 0x2e8, irq: 3, uartclk: 1843200 [ 0.740899] univ8250_console_setup: iobase: 0x3f8, irq: 4, uartclk: 1843200 [ 0.748623] serial8250_console_setup: iobase: 0x3f8, irq: 4, uartclk: 1843200 [ 0.756540] serial8250_console_setup: options: 115200 [ 0.762147] serial8250_console_setup: iobase: 0x3f8, irq: 4, uartclk: 1843200 [ 0.770064] printk: console [ttyS0] enabled <- univ8250_console [ 0.774789] printk: bootconsole [uart0] disabled ... nothing [ 1.224845] printk: console [ttyS0] enabled <- This is the AMDI0020:00 console getting loaded [ 1.229061] uart_add_one_port: Setting up console! [ 1.235099] serial8250_register_8250_port: Done! [ 1.239748] serial8250_register_8250_port: idx: 0, iobase: 0x0, membase: ffff96e70007d000, irq: 4, uartclk: 48000000 [ 1.250329] serial8250_register_8250_port: idx: 1, iobase: 0x2f8, membase: 0000000000000000, irq: 3, uartclk: 1843200 [ 1.260957] serial8250_register_8250_port: idx: 2, iobase: 0x3e8, membase: 0000000000000000, irq: 4, uartclk: 1843200 [ 1.271585] serial8250_register_8250_port: idx: 3, iobase: 0x2e8, membase: 0000000000000000, irq: 3, uartclk: 1843200 [ 1.282213] dw-apb-uart AMDI0020:00: RX: register port done [ 1.287897] dw-apb-uart AMDI0020:00: RX: set active [ 1.292805] dw-apb-uart AMDI0020:00: RX: done [ 1.297599] dw-apb-uart AMDI0020:01: RX: dw8250_probe: Probing UART [ 1.303976] dw-apb-uart AMDI0020:01: RX: UART Clock: 0 [ 1.309143] dw-apb-uart AMDI0020:01: RX: Overriding baud clock: 48000000 [ 1.315911] dw-apb-uart AMDI0020:01: RX: Quirks [ 1.320674] dw-apb-uart AMDI0020:01: RX: setup port [ 1.325665] dw-apb-uart AMDI0020:01: RX: setup port done [ 1.331007] dw-apb-uart AMDI0020:01: RX: register port ``` What would be the correct way to fix this? Should we probe the legacy (0x3f8) device before attaching univ8250_console so it doesn't override earlycon? Thanks, Raul
