linux-kernel - [PATCH] init: Don't proxy console= to earlycon

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Date:   Fri,  7 Jul 2023 19:17:25 -0600
From:   Raul E Rangel <rrangel@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     mario.limonciello@....com, kramasub@...omium.org,
        Raul E Rangel <rrangel@...omium.org>,
        Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Li Zhe <lizhe.67@...edance.com>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Mark Rutland <mark.rutland@....com>,
        Will Deacon <will@...nel.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Zhou jie <zhoujie@...china.com>
Subject: [PATCH] init: Don't proxy console= to earlycon

Right now we are proxying the `console=XXX` command line args to the
param_setup_earlycon. This is done because the following are
equivalent:

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

In addition, when `earlycon=` or just `earlycon` is specified on the
command line, we look at the SPCR table or the DT to extract the device
options.

When `console=` is specified on the command line, it's intention is to
disable the console. Right now since we are proxying the `console=`
flag to the earlycon handler, we enable the earlycon_acpi_spcr_enable
variable when an SPCR table is present. This means that we
inadvertently enable the earlycon.

This change makes it so we only proxy the console= command if it's
value is not empty. This way we can correctly handle both cases.

Signed-off-by: Raul E Rangel <rrangel@...omium.org>
---

 init/main.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/init/main.c b/init/main.c
index aa21add5f7c54..f72bf644910c1 100644
--- a/init/main.c
+++ b/init/main.c
@@ -738,8 +738,7 @@ static int __init do_early_param(char *param, char *val,
 	for (p = __setup_start; p < __setup_end; p++) {
 		if ((p->early && parameq(param, p->str)) ||
 		    (strcmp(param, "console") == 0 &&
-		     strcmp(p->str, "earlycon") == 0)
-		) {
+		     strcmp(p->str, "earlycon") == 0 && val && val[0])) {
 			if (p->setup_func(val) != 0)
 				pr_warn("Malformed early option '%s'\n", param);
 		}
-- 
2.41.0.255.g8b1d071c50-goog