@@ -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,
@@ -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);
}
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> --- I tested this patch with the following permutations: * console= * console * console=ttyS0,115200 * earlycon * earlycon=uart,mmio32,0xfedc9000 * earlycon= * console=uart,mmio32,0xfedc9000,115200n8 One unfortunate thing (unrelated to this patch) is that the `univ8250_console` registers as a real console (regardless if the legacy 0x3F8 UARTs are present) early on. This causes the `bootconsole` to get disabled and replaced with the non functional `univ8250_console`. [ 0.000000] earlycon: uart0 at MMIO32 0x00000000fedc9000 (options '') [ 0.000000] printk: legacy bootconsole [uart0] enabled ... [ 1.141835] printk: legacy console [ttyS0] enabled <-- Booo! [ 1.156500] printk: legacy bootconsole [uart0] disabled Changes in v2: - Switched to defining an early console parameter - Removed hack in main.c drivers/tty/serial/earlycon.c | 23 +++++++++++++++++++++++ init/main.c | 5 +---- 2 files changed, 24 insertions(+), 4 deletions(-)