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-rw-r--r--Documentation/ABI/testing/dev-kmsg27
1 files changed, 17 insertions, 10 deletions
diff --git a/Documentation/ABI/testing/dev-kmsg b/Documentation/ABI/testing/dev-kmsg
index 3c0bb76e3417..a377b6c093c9 100644
--- a/Documentation/ABI/testing/dev-kmsg
+++ b/Documentation/ABI/testing/dev-kmsg
@@ -6,6 +6,7 @@ Description: The /dev/kmsg character device node provides userspace access
to the kernel's printk buffer.
Injecting messages:
+
Every write() to the opened device node places a log entry in
the kernel's printk buffer.
@@ -21,6 +22,7 @@ Description: The /dev/kmsg character device node provides userspace access
the messages can always be reliably determined.
Accessing the buffer:
+
Every read() from the opened device node receives one record
of the kernel's printk buffer.
@@ -48,6 +50,7 @@ Description: The /dev/kmsg character device node provides userspace access
if needed, without limiting the interface to a single reader.
The device supports seek with the following parameters:
+
SEEK_SET, 0
seek to the first entry in the buffer
SEEK_END, 0
@@ -87,18 +90,22 @@ Description: The /dev/kmsg character device node provides userspace access
readable context of the message, for reliable processing in
userspace.
- Example:
- 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
+ Example::
+
+ 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
The DEVICE= key uniquely identifies devices the following way:
- b12:8 - block dev_t
- c127:3 - char dev_t
- n8 - netdev ifindex
- +sound:card0 - subsystem:devname
+
+ ============ =================
+ b12:8 block dev_t
+ c127:3 char dev_t
+ n8 netdev ifindex
+ +sound:card0 subsystem:devname
+ ============ =================
The flags field carries '-' by default. A 'c' indicates a
fragment of a line. Note, that these hints about continuation