Change IDs for kernel patches [LWN.net]

Change IDs for kernel patches

Posted Aug 30, 2019 9:21 UTC (Fri) by kleptog (subscriber, #1183)
Parent article: Change IDs for kernel patches

> Linus Torvalds was quick to reject the idea of putting a bare change ID into patch changelogs, citing the same reasoning that has kept those IDs out thus far: they are really only useful to whoever put that ID into the changelog in the first place.

I find this an odd comment. Given the ID is effectively a globally unique string, simply throwing the Change-ID into $SEARCHENGINE will immediately return any and all mail conversations, bug trackers, etc referring to this patch. This seems much more useful that some email message ID, which is not easily searchable because it contains so many word-breaking characters and significant constant parts.

In any case, even in Gerrit you don't really use those Change-IDs to search for patches, each change has an actual URL too, but that doesn't appear in the commit while it's under discussion. The Change-ID is mostly useful after the fact to locate patches that are related.

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Change IDs for kernel patches

Posted Sep 3, 2019 4:25 UTC (Tue) by Fowl (subscriber, #65667) [Link] (2 responses)

> Given the ID is effectively a globally unique string

Indeed - I'm not sure why an actual GUID wouldn't work, they're shorter and don't require mailing anything. I guess they're a bit Microsoft-y.

Couldn't a first/arbitrary comit hash become the 'change ID'? Even if that exact commit never ends up in a tree it's a shortish, unique string that doesn't require any new tooling to generate.

Change IDs for kernel patches

Posted Sep 3, 2019 6:50 UTC (Tue) by khim (subscriber, #9252) [Link] (1 responses)

> Couldn't a first/arbitrary comit hash become the 'change ID'?

You don't really need it: it's highly likely that this particular commit would only exist on a developer's machine and would never be posted.

Change-Id: used by Gerrit is not really created by Gerrit - that's just a random string which git presubmit hook adds to the description if it's not there.

This is done that way precisely because Android developers don't have a central Gerrit server: there are bazillion of them - each vendor have one, Google have half-dozen and so on.

Change-Id just allows you to do a search, nothing more, nothing less.

Change IDs for kernel patches

Posted Sep 3, 2019 7:14 UTC (Tue) by Fowl (subscriber, #65667) [Link]

> You don't really need it: it's highly likely that this particular commit would only exist on a developer's machine and would never be posted.

And this confusion is probably the flaw in the idea - once people read 'commit hash' they'll be assume it's a commit they can find. ;)

Change IDs for kernel patches

Posted Sep 5, 2019 8:54 UTC (Thu) by marcH (subscriber, #57642) [Link]

> I find this an odd comment

It's not just odd, it's plain wrong.

Change-Id are being re-used across Gerrit instances and across branches and it works great.