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-rw-r--r--Documentation/admin-guide/kernel-parameters.txt19
1 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2deccf57ecee..6a597e911e9c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -792,6 +792,25 @@
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]