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authorKay Sievers <kay@vrfy.org>2012-07-16 18:35:30 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-16 18:35:30 -0700
commitd39f3d77c9b1fe7cc33a14beb4a4849af0a4ac22 (patch)
treebf3a4fd34aa850a5f30f966dfd98a40a424f6b9a /Documentation/ABI
parent96efedf1491cdf0616e5e4fff0711cebf20f69c7 (diff)
downloadop-kernel-dev-d39f3d77c9b1fe7cc33a14beb4a4849af0a4ac22.zip
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kmsg - export "continuation record" flag to /dev/kmsg
In some cases we are forced to store individual records for a continuation line print. Export a flag to allow the external re-construction of the line. The flag allows us to apply a similar logic externally which is used internally when the console, /proc/kmsg or the syslog() output is printed. $ cat /dev/kmsg 4,165,0,-;Free swap = 0kB 4,166,0,-;Total swap = 0kB 6,167,0,c;[ 4,168,0,+;0 4,169,0,+;1 4,170,0,+;2 4,171,0,+;3 4,172,0,+;] 6,173,0,-;[0 1 2 3 ] 6,174,0,-;Console: colour VGA+ 80x25 6,175,0,-;console [tty0] enabled Signed-off-by: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/dev-kmsg29
1 files changed, 20 insertions, 9 deletions
diff --git a/Documentation/ABI/testing/dev-kmsg b/Documentation/ABI/testing/dev-kmsg
index 281ecc5..7e7e07a 100644
--- a/Documentation/ABI/testing/dev-kmsg
+++ b/Documentation/ABI/testing/dev-kmsg
@@ -58,16 +58,18 @@ Description: The /dev/kmsg character device node provides userspace access
The output format consists of a prefix carrying the syslog
prefix including priority and facility, the 64 bit message
- sequence number and the monotonic timestamp in microseconds.
- The values are separated by a ','. Future extensions might
- add more comma separated values before the terminating ';'.
- Unknown values should be gracefully ignored.
+ sequence number and the monotonic timestamp in microseconds,
+ and a flag field. All fields are separated by a ','.
+
+ Future extensions might add more comma separated values before
+ the terminating ';'. Unknown fields and values should be
+ gracefully ignored.
The human readable text string starts directly after the ';'
and is terminated by a '\n'. Untrusted values derived from
hardware or other facilities are printed, therefore
- all non-printable characters in the log message are escaped
- by "\x00" C-style hex encoding.
+ all non-printable characters and '\' itself in the log message
+ are escaped by "\x00" C-style hex encoding.
A line starting with ' ', is a continuation line, adding
key/value pairs to the log message, which provide the machine
@@ -75,11 +77,11 @@ Description: The /dev/kmsg character device node provides userspace access
userspace.
Example:
- 7,160,424069;pci_root PNP0A03:00: host bridge window [io 0x0000-0x0cf7] (ignored)
+ 7,160,424069,-;pci_root PNP0A03:00: host bridge window [io 0x0000-0x0cf7] (ignored)
SUBSYSTEM=acpi
DEVICE=+acpi:PNP0A03:00
- 6,339,5140900;NET: Registered protocol family 10
- 30,340,5690716;udevd[80]: starting version 181
+ 6,339,5140900,-;NET: Registered protocol family 10
+ 30,340,5690716,-;udevd[80]: starting version 181
The DEVICE= key uniquely identifies devices the following way:
b12:8 - block dev_t
@@ -87,4 +89,13 @@ Description: The /dev/kmsg character device node provides userspace access
n8 - netdev ifindex
+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
+ neccessarily 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.
+
Users: dmesg(1), userspace kernel log consumers
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