Advice appreciated. Thanks,
- mulhern ----- Forwarded Message ----- > From: "Anne Mulhern" <amulh...@redhat.com> > To: "OS Development List" <os-devel-l...@redhat.com> > Sent: Thursday, July 9, 2015 4:46:13 PM > Subject: kernel logging_journald_journalctl question > > Hi! > > My ultimate goal is that the following example line: > > "journalctl _WWN=wwn-0x5002e10000000000" > > should be meaningful, i.e., > * yield all log messages pertaining to a device w/ that particular wwn > * the _WWN value should be guaranteed with the same certainty as journalctl's > other unfakeable values with underscores, e.g., _UID. > > One subgoal is, therefore, to make sure that _correct_ _WWN information gets > into > the journal when that information is available. > > In principle, journal messages about devices that possess WWN's might > originate in a > variety of places. This makes things complicated, since it is possible that > the appropriate way of discovering the WWN may vary with the origin of the > message. > (For example, lsscsi discovers the WWN of the current device by searching > /dev/disk/by-id/.) > > However, I'm focusing on messages that originate in the kernel via > dev_printk() in > the SCSI mid-layer. I infer that journald reads them from the kernel log > buffer in the > dev_kmsg_record() method. I also know that dev_printk guarantees to print two > key/value pairs, > SUBSYSTEM and DEVICE. > > What is the best way to make information about the WWN available to journald? > Can it reliably extract this information from the DEVICE field in the > dev_kmsg_record() > method? Is there a process that I don't know about that picks up messages > from the kernel > and augments them with extra metadata before they end up in /dev/kmsg that > can be modified? > Would dev_printk() itself have to be extended to include WWN information as > another field > in addition to SUBSYSTEM and DEVICE? Must I fall back on making sure that > individual calls > to dev_printk() include some essential information that can be parsed back > out by journald? > > It would also be nice to take into consideration that messages regarding > devices could > be logged from other sources, like the journald API, and it would be nice to > reliably store > the WWN information from those messages in the journal, as well. > > Thanks in advance for any help, > > - mulhern > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel