From 17199dfccd4b7f7e0c059ef43bef6e0078423476 Mon Sep 17 00:00:00 2001 From: Tony Lindgren <tony@atomide.com> Date: Wed, 3 Jul 2024 13:06:10 +0300 Subject: [PATCH] Documentation: kernel-parameters: Add DEVNAME:0.0 format for serial ports Document the console option for DEVNAME:0.0 style addressing for serial ports. Suggested-by: Sebastian Reichel <sre@kernel.org> Signed-off-by: Tony Lindgren <tony@atomide.com> Reviewed-by: Dhruva Gole <d-gole@ti.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20240703100615.118762-4-tony.lindgren@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- .../admin-guide/kernel-parameters.txt | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 27ec49af1bf27..11e57ba2985cc 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -788,6 +788,25 @@ Documentation/networking/netconsole.rst for an alternative. + <DEVNAME>:<n>.<n>[,options] + Use the specified serial port on the serial core bus. + The addressing uses DEVNAME of the physical serial port + device, followed by the serial core controller instance, + and the serial port instance. The options are the same + as documented for the ttyS addressing above. + + The mapping of the serial ports to the tty instances + can be viewed with: + + $ ls -d /sys/bus/serial-base/devices/*:*.*/tty/* + /sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0 + + In the above example, the console can be addressed with + console=00:04:0.0. Note that a console addressed this + way will only get added when the related device driver + is ready. The use of an earlycon parameter in addition to + the console may be desired for console output early on. + uart[8250],io,<addr>[,options] uart[8250],mmio,<addr>[,options] uart[8250],mmio16,<addr>[,options] -- GitLab