Commit 99645717 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Ingo Molnar
Browse files

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



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: 3181424a ("x86/early_printk: Add support for MMIO-based UARTs")
Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarDenis Mukhin <dmukhin@ford.com>
Link: https://lore.kernel.org/r/20250407172214.792745-1-andriy.shevchenko@linux.intel.com
parent 45c2e30b

Documentation/admin-guide/kernel-parameters.txt

+1 −4
Original line number Diff line number Diff line
@@ -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.

arch/x86/kernel/early_printk.c

+5 −5
Original line number Diff line number Diff line
@@ -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) &&