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>

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index a5fbb6ed38aed6817eb32fc26d2ea0b72bad126c..ab9af37f6cda35ea2e3ea966fdac8ba5c4475cb2 100644 (file)
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -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,

diff --git a/init/main.c b/init/main.c
index c4778edae7972f512d5eefe8400075ac35a70d1c..00fac1170294f547a3a4252b7006f04aeb2fa937 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -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);
                }