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-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 281ecc5f970..7e7e07a82e0 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