Re: [patch] early printk and boot console fixups.

["Yinghai Lu" <yhlu.kernel@gmail.com>]

On 2/16/07, Gerd Hoffmann <kraxel@suse.de> wrote:

> The console subsystem already has an idea of a boot console, using the
> CON_BOOT flag.  The implementation has some flaws though.  The major
> problem is that presence of a boot console makes register_console()
> ignore any other console devices (unless explicitly specified on the
> kernel command line).
>
> This patch fixes the console selection code to *not* consider a boot
> console a full-featured one, so the first "normal" console registering
> will become the default boot console instead.  This way the unregister
> call for the boot console in register_console() actually triggers and
> the handover from the boot console to the real console device works
> smoothly.
>
> The patch also changes the x86 early_printk code to use this.  The early
> console is simply tagged as boot console, the disable_early_printk()
> call is gone as it isn't needed any more.

just notice console handover patch got into mainline 5/8.

for early_uart_console, I have some ideas:
1. merged that into early_serial_console in
arch/x86_64/kernel/early_printk.c, and
move early_printk.c to kernel/, --- make it understand
     earlyprintk=uart,io,0x3f8,9600n8
     earlyprintk=uart,mmio,0xff5e0000,115200n8
in addition to vga, ttyS, serial

2. or make early_uart_console to be another CON_BOOT, and get rid of
late_initcall(early_uart_console_switch).
actually with late_initcall early_uart_console_switch instead of
console handover, we will lose char output from serial drv init to
late_initcall stage.
in this case, we need to EARLY_SERIAL_CONSOLE to select
early_serial_console or early_uart_console for x86_64 platform.

YH