diff options
Diffstat (limited to 'Documentation/ABI/testing/dev-kmsg')
| -rw-r--r-- | Documentation/ABI/testing/dev-kmsg | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/Documentation/ABI/testing/dev-kmsg b/Documentation/ABI/testing/dev-kmsg index 1e6c28b1942b..3c0bb76e3417 100644 --- a/Documentation/ABI/testing/dev-kmsg +++ b/Documentation/ABI/testing/dev-kmsg @@ -56,10 +56,16 @@ Description: The /dev/kmsg character device node provides userspace access seek after the last record available at the time the last SYSLOG_ACTION_CLEAR was issued. - Due to the record nature of this interface with a "read all" - behavior and the specific positions each seek operation sets, - SEEK_CUR is not supported, returning -ESPIPE (invalid seek) to - errno whenever requested. + Other seek operations or offsets are not supported because of + the special behavior this device has. The device allows to read + or write only whole variable length messages (records) that are + stored in a ring buffer. + + Because of the non-standard behavior also the error values are + non-standard. -ESPIPE is returned for non-zero offset. -EINVAL + is returned for other operations, e.g. SEEK_CUR. This behavior + and values are historical and could not be modified without the + risk of breaking userspace. The output format consists of a prefix carrying the syslog prefix including priority and facility, the 64 bit message |