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SubjectRe: [PATCH 1/1] tty/serial: to support 8250 earlycon can be enabled independently
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On 05/16/2016 04:35 AM, Zhen Lei wrote:
> Sometimes, we may only use SSH to login, and build 8250 uart driver as a
> ko(insmod if needed). But the earlycon may still be necessary, because
> the kernel boot process may take a long time. It's not good to display
> nothing but ask people to wait patiently.

I'm confused; you want the possibility of earlycon but _not_ a normal
serial console?

This configuration is unsafe because nothing prevents the 8250 driver
and 8250 earlycon from concurrently accessing the hardware.


> In addition, the 8250.ko can not be worked if we have not opened any
> other serial drivers, because SERIAL_CORE would not be selected.

I don't understand what this means.

Regards,
Peter Hurley


> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
> drivers/tty/serial/8250/Kconfig | 9 +++++++--
> drivers/tty/serial/8250/Makefile | 1 -
> drivers/tty/serial/Makefile | 1 +
> 3 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> index 4d7cb9c..2992f0a 100644
> --- a/drivers/tty/serial/8250/Kconfig
> +++ b/drivers/tty/serial/8250/Kconfig
> @@ -3,6 +3,12 @@
> # you somehow have an implicit or explicit dependency on SERIAL_8250.
> #
>
> +config SERIAL_8250_EARLYCON
> + bool "Early console using 8250"
> + select SERIAL_CORE
> + select SERIAL_CORE_CONSOLE
> + select SERIAL_EARLYCON
> +
> config SERIAL_8250
> tristate "8250/16550 and compatible serial support"
> select SERIAL_CORE
> @@ -60,8 +66,7 @@ config SERIAL_8250_PNP
> config SERIAL_8250_CONSOLE
> bool "Console on 8250/16550 and compatible serial port"
> depends on SERIAL_8250=y
> - select SERIAL_CORE_CONSOLE
> - select SERIAL_EARLYCON
> + select SERIAL_8250_EARLYCON
> ---help---
> If you say Y here, it will be possible to use a serial port as the
> system console (the system console is the device which receives all
> diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
> index c9a2d6e..1f24c74 100644
> --- a/drivers/tty/serial/8250/Makefile
> +++ b/drivers/tty/serial/8250/Makefile
> @@ -13,7 +13,6 @@ obj-$(CONFIG_SERIAL_8250_HP300) += 8250_hp300.o
> obj-$(CONFIG_SERIAL_8250_CS) += serial_cs.o
> obj-$(CONFIG_SERIAL_8250_ACORN) += 8250_acorn.o
> obj-$(CONFIG_SERIAL_8250_BCM2835AUX) += 8250_bcm2835aux.o
> -obj-$(CONFIG_SERIAL_8250_CONSOLE) += 8250_early.o
> obj-$(CONFIG_SERIAL_8250_FOURPORT) += 8250_fourport.o
> obj-$(CONFIG_SERIAL_8250_ACCENT) += 8250_accent.o
> obj-$(CONFIG_SERIAL_8250_BOCA) += 8250_boca.o
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index 8c261ad..cd84181 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_SERIAL_SUNSAB) += sunsab.o
>
> # Now bring in any enabled 8250/16450/16550 type drivers.
> obj-$(CONFIG_SERIAL_8250) += 8250/
> +obj-$(CONFIG_SERIAL_8250_EARLYCON) += 8250/8250_early.o
>
> obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
> obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
> --
> 2.5.0
>
>
> --
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