On Wed, 11 Jul 2018, Alexandre Belloni wrote:
> Parse and use the keep parameter of earlyprintk to avoid having the kernel
> output stop with:
>
> Console: colour dummy device 80x30
> console [tty0] enabled
> bootconsole [earlycon0] disabled
>
> This happens because once tty0, the virtual terminal console is registered,
> it is selected as the default console, disregarding an existing stdout-path
> DT property and the early console is shutdown before the console driver is
> probed.
>
> Signed-off-by: Alexandre Belloni <[email protected]>
Why can't you have a real console driver that takes over at that point
which respects whatever DT property you give it?
The early_printk code is very raw and inefficient, and it shouldn't be
used for anything but the debugging of early boot hangs.
> ---
> arch/arm/kernel/early_printk.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm/kernel/early_printk.c b/arch/arm/kernel/early_printk.c
> index 9257736ec9fa..bbb10150b11a 100644
> --- a/arch/arm/kernel/early_printk.c
> +++ b/arch/arm/kernel/early_printk.c
> @@ -42,6 +42,9 @@ static struct console early_console_dev = {
>
> static int __init setup_early_printk(char *buf)
> {
> + if (buf && strstr(buf, "keep"))
> + early_console_dev.flags &= ~CON_BOOT;
> +
> early_console = &early_console_dev;
> register_console(&early_console_dev);
> return 0;
> --
> 2.18.0
>
>
