Systemd 197 released

Posted Jan 8, 2013 21:26 UTC (Tue) by mezcalero (subscriber, #45103)
In reply to: Systemd 197 released by dave_malcolm
Parent article: Systemd 197 released

They are allowed, but interface names are limited to IFNAMSIZ characters, and that's defined to 16 on Linux (and can't realistically be changed), of which one must be the trailing 0. That means you have only 15 chars. A MAC address formatted in hex requires 12 characters. That means you only have 3 characters left for the prefix. An underscore is hence a luxury you can't afford. WE could use it for the other policies, but 15 chars for them is not plentiful either (think about USB device paths!), and uniformity is kinda nice too.

Systemd 197 released

Posted Jan 8, 2013 21:51 UTC (Tue) by jimparis (guest, #38647) [Link] (1 responses)

It's not really clear from the documentation -- what happens if the USB path doesn't fit in 15 characters?

Systemd 197 released

Posted Jan 8, 2013 22:52 UTC (Tue) by mezcalero (subscriber, #45103) [Link]

Then we won't use that name. The rule is basically: if the chosen policy makes sense for a device, all the necessary information for it is available for a device, and if the name would fit in IFNAMSIZ then we use it, otherwise we give up, and try another policy, or just stick to the kernel name.

Systemd 197 released

Posted Jan 9, 2013 2:30 UTC (Wed) by dave_malcolm (subscriber, #15013) [Link]

Aha! Given that constraint, it makes sense. Thanks.

Systemd 197 released

Posted Jan 9, 2013 5:34 UTC (Wed) by jthill (subscriber, #56558) [Link]

Does anyone value being able to sight-read the actual address values? Why not base64 them?

Systemd 197 released

Posted Jan 9, 2013 23:18 UTC (Wed) by mathstuf (subscriber, #69389) [Link] (5 responses)

> but interface names are limited to IFNAMSIZ characters

I suppose there's a 'DFINSIZ' limit for the length of variable names too. Either that or the 'E' key was broken that day…

Systemd 197 released

Posted Jan 9, 2013 23:53 UTC (Wed) by Cyberax (✭ supporter ✭, #52523) [Link] (4 responses)

Yeah, and they also were not careful - one vowel accidentally got in. Standards are slipping these days...

I always wondered how EIEIO did happen.

Systemd 197 released

Posted Jan 10, 2013 11:20 UTC (Thu) by mgedmin (subscriber, #34497) [Link]

IBM motto: "We found five vowels hiding in a corner, and we used
them _all_ for the 'eieio' instruction so that we wouldn't have to use
them anywhere else"
-- Linus Torvalds

Systemd 197 released

Posted Jan 11, 2013 20:30 UTC (Fri) by pcarrier (guest, #65446) [Link] (2 responses)

I always assumed it was a pun on the “Old MacDonald had a farm” lyrics.

http://en.wikipedia.org/wiki/Old_MacDonald_Had_a_Farm

Systemd 197 released

Posted Jan 11, 2013 20:49 UTC (Fri) by s_hoop (guest, #49503) [Link]

I have heard this before too. Seems likely to me based on this anecdata ;-)

Systemd 197 released

Posted Jan 12, 2013 10:19 UTC (Sat) by zwenna (guest, #64777) [Link]

Indeed, the error message corresponding to EIEIO is Computer bought the farm.