Commit 17b65575 authored Sep 11, 2024 by Raul E Rangel Committed by Petr Mladek Oct 01, 2024

init: Don't proxy `console=` to earlycon



Today we are proxying the `console=` command line args to the
`param_setup_earlycon()` handler. This is done because the following are
equivalent:

    console=uart[8250],mmio,<addr>[,options]
    earlycon=uart[8250],mmio,<addr>[,options]

Both invocations enable an early `bootconsole`. `console=uartXXXX` is
just an alias for `earlycon=uartXXXX`.

In addition, when `earlycon=` (empty value) or just `earlycon`
(no value) is specified on the command line, we enable the earlycon
`bootconsole` specified by the SPCR table or the DT.

The problem arises when `console=` (empty value) is specified on the
command line. It's intention is to disable the `console`, but what
happens instead is that the SPRC/DT console gets enabled.

This happens because we are proxying the `console=` (empty value)
parameter to the `earlycon` handler. The `earlycon` handler then sees
that the parameter value is empty, so it enables the SPCR/DT
`bootconsole`.

This change makes it so that the `console` or `console=` parameters no
longer enable the SPCR/DT `bootconsole`. I also cleans up the hack in
`main.c` that would forward the `console` parameter to the `earlycon`
handler.

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240911123507.v2.1.Id08823b2f848237ae90ce5c5fa7e027e97c33ad3@changeid


Signed-off-by: Petr Mladek <pmladek@suse.com>

parent c903327d

drivers/tty/serial/earlycon.c

+23 −0

Original line number	Diff line number	Diff line
		@@ -248,6 +248,29 @@ static int __init param_setup_earlycon(char *buf)
		}
		early_param("earlycon", param_setup_earlycon);

		/*
		* The `console` parameter is overloaded. It's handled here as an early param
		* and in `printk.c` as a late param. It's possible to specify an early
		* `bootconsole` using `earlycon=uartXXXX` (handled above), or via
		* the `console=uartXXX` alias. See the comment in `8250_early.c`.
		*/
		static int __init param_setup_earlycon_console_alias(char *buf)
		{
		/*
		* A plain `console` parameter must not enable the SPCR `bootconsole`
		* like a plain `earlycon` does.
		*
		* A `console=` parameter that specifies an empty value is used to
		* disable the `console`, not the `earlycon` `bootconsole`. The
		* disabling of the `console` is handled by `printk.c`.
		*/
		if (!buf \|\| !buf[0])
		return 0;

		return param_setup_earlycon(buf);
		}
		early_param("console", param_setup_earlycon_console_alias);

		#ifdef CONFIG_OF_EARLY_FLATTREE

		int __init of_setup_earlycon(const struct earlycon_id *match,

init/main.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -754,10 +754,7 @@ static int __init do_early_param(char param, char val,
		const struct obs_kernel_param *p;

		for (p = __setup_start; p < __setup_end; p++) {
		if ((p->early && parameq(param, p->str)) \|\|
		(strcmp(param, "console") == 0 &&
		strcmp(p->str, "earlycon") == 0)
		) {
		if (p->early && parameq(param, p->str)) {
		if (p->setup_func(val) != 0)
		pr_warn("Malformed early option '%s'\n", param);
		}