Commit 085a3a8f authored by James Byrne's avatar James Byrne Committed by Petr Mladek
Browse files

ABI: Update dev-kmsg documentation to match current kernel behaviour 

Commit 5aa068ea ("printk: remove games with previous record flags")
abolished the practice of setting the log flag to 'c' for the first
continuation line and '+' for subsequent lines. Now all continuation
lines are flagged with 'c' and '+' is never used.

Update the 'dev-kmsg' documentation to remove the reference to the
obsolete '+' flag. In addition, state explicitly that only 8 bits of the
<N> syslog prefix are used for the facility number when writing to
/dev/kmsg.

Link: http://lkml.kernel.org/r/0102016cf1b26630-8e9b337b-da49-43c6-b028-4250c2fac3ef-000000@eu-west-1.amazonses.com


Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarJames Byrne <james.byrne@origamienergy.com>
Reviewed-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent 35c35493

Documentation/ABI/testing/dev-kmsg

+7 −8
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ Description: The /dev/kmsg character device node provides userspace access 
		The logged line can be prefixed with a <N> syslog prefix, which

		carries the syslog priority and facility. The single decimal

		prefix number is composed of the 3 lowest bits being the syslog

		priority and the higher bits the syslog facility number.

		priority and the next 8 bits the syslog facility number.



		If no prefix is given, the priority number is the default kernel

		log priority and the facility number is set to LOG_USER (1). It
@@ -90,13 +90,12 @@ Description: The /dev/kmsg character device node provides userspace access 
		  +sound:card0 - subsystem:devname



		The flags field carries '-' by default. A 'c' indicates a

		fragment of a line. All following fragments are flagged with

		'+'. Note, that these hints about continuation lines are not

		necessarily correct, and the stream could be interleaved with

		unrelated messages, but merging the lines in the output

		usually produces better human readable results. A similar

		logic is used internally when messages are printed to the

		console, /proc/kmsg or the syslog() syscall.

		fragment of a line. Note, that these hints about continuation

		lines are not necessarily correct, and the stream could be

		interleaved with unrelated messages, but merging the lines in

		the output usually produces better human readable results. A

		similar logic is used internally when messages are printed to

		the console, /proc/kmsg or the syslog() syscall.



		By default, kernel tries to avoid fragments by concatenating

		when it can and fragments are rare; however, when extended

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