From 18a8bd949d6adb311ea816125ff65050df1f3f6e Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Sun, 15 Jul 2007 23:37:59 -0700 Subject: serial: convert early_uart to earlycon for 8250 Beacuse SERIAL_PORT_DFNS is removed from include/asm-i386/serial.h and include/asm-x86_64/serial.h. the serial8250_ports need to be probed late in serial initializing stage. the console_init=>serial8250_console_init=> register_console=>serial8250_console_setup will return -ENDEV, and console ttyS0 can not be enabled at that time. need to wait till uart_add_one_port in drivers/serial/serial_core.c to call register_console to get console ttyS0. that is too late. Make early_uart to use early_param, so uart console can be used earlier. Make it to be bootconsole with CON_BOOT flag, so can use console handover feature. and it will switch to corresponding normal serial console automatically. new command line will be: console=uart8250,io,0x3f8,9600n8 console=uart8250,mmio,0xff5e0000,115200n8 or earlycon=uart8250,io,0x3f8,9600n8 earlycon=uart8250,mmio,0xff5e0000,115200n8 it will print in very early stage: Early serial console at I/O port 0x3f8 (options '9600n8') console [uart0] enabled later for console it will print: console handover: boot [uart0] -> real [ttyS0] Signed-off-by: Cc: Andi Kleen Cc: Bjorn Helgaas Cc: Russell King Cc: Gerd Hoffmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/serial/Kconfig | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'drivers/serial/Kconfig') diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index 2adbed4e10f..cab42cbd920 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -62,8 +62,22 @@ config SERIAL_8250_CONSOLE kernel will automatically use the first serial line, /dev/ttyS0, as system console. + you can set that using a kernel command line option such as + "console=uart8250,io,0x3f8,9600n8" + "console=uart8250,mmio,0xff5e0000,115200n8". + and it will switch to normal serial console when correponding port is + ready. + "earlycon=uart8250,io,0x3f8,9600n8" + "earlycon=uart8250,mmio,0xff5e0000,115200n8". + it will not only setup early console. + If unsure, say N. +config FIX_EARLYCON_MEM + bool + depends on X86 + default y + config SERIAL_8250_GSC tristate depends on SERIAL_8250 && GSC -- cgit v1.2.3