The hwdb behaviour is a bit hard to predict when multiple matches with globs apply to a device so I'm wondering whether this is just an implementation result or intended behaviour.
Example 1: $> cat 99-test.hwdb test:* match=generic test:specific* match=specific $> systemd-hwdb query "test:specific_match" match=specific This is what I would expect from the hwdb entries. But if we have a rule where glob matches before specific, the generic one overwrites the specific one: Example 2: $> cat 99-test.hwdb test:* match=generic test:*specific* match=specific match2=yep $> systemd-hwdb query "test:specific_match" match=generic match2=yep Definitely not what I expected (note: the order of the entries doesn't matter). This is actually a problem for libinput because it means we can't overwrite generic matches with specific matches. But it gets even weirder once we start stacking more: Example 3: $> cat 99-test.hwdb test:* match=generic test:*specific* match=specific match2=yep test:*specific_match match=specific match2=nope match3=yep $> sudo systemd-hwdb query "test:specific_match" match=generic match2=nope match3=yep It picks the most generic one last but the more specific one over the less specific one. This is confusing and hard to predict. But it gets worse: Example 4: $> cat 99-test.hwdb test:* match=generic test:*specific* match=specific match2=yep test:*spe*match match=specific match2=nope match3=yep test:*specific*match match=specific match2=oh match3=what match4=confused $> sudo systemd-hwdb query "test:specific_match" match=generic match2=yep match3=what match4=confused And now I'm lost :) As a homework, try predicting what this one produces: Exercise: test:* MATCH=generic # changing this to test:specific gives different results test:*specific* MATCH=specific MATCH2=yep test:*spe*match MATCH=specific MATCH2=nope MATCH3=yep test:*specific_* MATCH=specific MATCH2=oh MATCH3=crap MATCH4=what? test:*specific*match MATCH=specific MATCH2=doh MATCH3=what MATCH4=confused MATCH5=boo Solution: "generic, oh, crap, what?, boo" with the glob, without the glob it's "specific, yep, crap, what?, boo" So the question is: is this the intended behaviour (if so, we should document it and make it official) or is this a side-effect. If that, can we change it or is it set in stone? I think no-one but me is currently eagerly stacking hwdb snippets, so maybe there's room to move. As for expected behaviour, I'd intuitively expect a more sequential matching, with an entry in 99-test.hwd overwriting whatever entry was in 10-test.hwdb. Cheers, Peter _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
