[PATCH v1 1/1] x86/early_printk: Use 'mmio32' for consistency
From: Andy Shevchenko
Date: Mon Apr 07 2025 - 13:23:15 EST
First of all, using 'mmio' prevents proper implementation of 8-bit accessors.
Second, it's simply inconsistent with uart8250 set of options. Rename it to
'mmio32'. While at it, remove rather misleading comment in the documentation.
>From now on mmio32 is self-explanatory and pciserial supports not only 32-bit
MMIO accessors.
Fixes: 3181424aeac2 ("x86/early_printk: Add support for MMIO-based UARTs")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 5 +----
arch/x86/kernel/early_printk.c | 6 +++---
2 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 76e538c77e31..d9fd26b95b34 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1407,18 +1407,15 @@
earlyprintk=serial[,0x...[,baudrate]]
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
+ earlyprintk=mmio32,membase[,{nocfg|baudrate}]
earlyprintk=pciserial[,force],bus:device.function[,{nocfg|baudrate}]
earlyprintk=xdbc[xhciController#]
earlyprintk=bios
- earlyprintk=mmio,membase[,{nocfg|baudrate}]
earlyprintk is useful when the kernel crashes before
the normal console is initialized. It is not enabled by
default because it has some cosmetic problems.
- Only 32-bit memory addresses are supported for "mmio"
- and "pciserial" devices.
-
Use "nocfg" to skip UART configuration, assume
BIOS/firmware has configured UART correctly.
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index b70e6e99fb17..dc053641698c 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -424,10 +424,10 @@ static int __init setup_early_printk(char *buf)
keep = (strstr(buf, "keep") != NULL);
while (*buf != '\0') {
- if (!strncmp(buf, "mmio", 4)) {
- early_mmio_serial_init(buf + 4);
+ if (!strncmp(buf, "mmio32", 6)) {
+ buf += 6;
+ early_mmio_serial_init(buf);
early_console_register(&early_serial_console, keep);
- buf += 4;
}
if (!strncmp(buf, "serial", 6)) {
buf += 6;
--
2.47.2