Re: [PATCH blktests] Add use of logger so that syslog files show when each test starts

["Theodore Y. Ts'o" <tytso@mit.edu>]

On Mon, Nov 26, 2018 at 09:50:57AM -0800, Omar Sandoval wrote:
> 
> Hey, Ted, sorry, I meant to ask you about this in person at LPC but
> forgot to. Forgive my ignorance about syslog, but does syslog not pick
> up the line we write to dmesg?

Unfortunately, it does not.

root@xfstests-ltm:~# echo foo testing >> /dev/kmsg 
root@xfstests-ltm:~# dmesg | tail
[    7.103899] random: crng init done
[    7.104759] random: 7 urandom warning(s) missed due to ratelimiting
[    7.154525] EDAC MC: Ver: 3.0.0
[    7.221973] EDAC sbridge: Seeking for: PCI ID 8086:2fa0
[    7.221977] EDAC sbridge:  Ver: 1.1.1 
[    7.259154] device-mapper: uevent: version 1.0.3
[    7.267252] device-mapper: ioctl: 4.35.0-ioctl (2016-06-23) initialised: dm-devel@redhat.com
[    7.762306] EXT4-fs (sda1): resizing filesystem from 2620928 to 13106683 blocks
[    8.541258] EXT4-fs (sda1): resized filesystem to 13106683
[840160.646340] foo testing
root@xfstests-ltm:~# tail /var/log/kern.log
root@xfstests-ltm:~# grep kern.log /etc/rsyslog.conf 
kern.*				-/var/log/kern.log

So as you can see nothing written to kern.log, even though we wrote to
/dev/kmsg.

To prove that kern.log will get kernel messages:

root@xfstests-ltm:~# mke2fs -t ext4 -Fq /tmp/foo.img 8M
root@xfstests-ltm:~# mount -t ext4 /tmp/foo.img /mnt
root@xfstests-ltm:~# echo testing > /sys/fs/ext4/loop0/trigger_fs_error 
root@xfstests-ltm:~# tail /var/log/kern.log
Nov 26 13:30:22 xfstests-ltm kernel: [840286.728296] loop: module loaded
Nov 26 13:30:22 xfstests-ltm kernel: [840286.752181] EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null)
Nov 26 13:30:41 xfstests-ltm kernel: [840305.773418] EXT4-fs error (device loop0): trigger_test_error:123: comm bash: testing
root@xfstests-ltm:~# 

					- Ted