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x86/early_printk: Use 'mmio32' for consistency, fix comments

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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.

Also, while at it, fix the comment for the "pciserial" case. The comment
seems to be a copy'n'paste error when mentioning "serial" instead of
"pciserial" (with double quotes). Fix this.

With that, move it upper, so we don't calculate 'buf' twice.

Fixes: 3181424aea ("x86/early_printk: Add support for MMIO-based UARTs")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Link: https://lore.kernel.org/r/20250407172214.792745-1-andriy.shevchenko@linux.intel.com
This commit is contained in:
Andy Shevchenko 2025-04-07 20:22:14 +03:00 committed by Ingo Molnar
parent 45c2e30bbd
commit 996457176b
2 changed files with 6 additions and 9 deletions
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5
Documentation/admin-guide/kernel-parameters.txt
View File

@ -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.

10
arch/x86/kernel/early_printk.c
View File

@ -389,10 +389,10 @@ 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;
@ -407,9 +407,9 @@ static int __init setup_early_printk(char *buf)
}
#ifdef CONFIG_PCI
if (!strncmp(buf, "pciserial", 9)) {
early_pci_serial_init(buf + 9);
buf += 9; /* Keep from match the above "pciserial" */
early_pci_serial_init(buf);
early_console_register(&early_serial_console, keep);
buf += 9; /* Keep from match the above "serial" */
}
#endif
if (!strncmp(buf, "vga", 3) &&