[systemd-devel] [PATCH 1/2] libsystemd: add sd-hwdb library

Greg KH gregkh at linuxfoundation.org
Wed Dec 3 16:53:29 PST 2014

On Thu, Dec 04, 2014 at 12:57:53AM +0100, Tom Gundersen wrote:
> On Wed, Dec 3, 2014 at 10:19 PM, Greg KH <gregkh at linuxfoundation.org> wrote:
> > On Wed, Dec 03, 2014 at 10:11:40PM +0100, Tom Gundersen wrote:
> >> This is libudev-hwdb, but decoupled from libudev and in the libsystemd style.
> >>
> >> The core code is unchanged, apart from the following minor changes:
> >>
> >>  - hwdb.bin located in /**/systemd/hwdb/ take preference over the ones located
> >>    in /**/udev/
> >>  - properties are stored internally in an OrderedHashmap, rather than a
> >>    linked list.
> >>  - a new API call allows individual properties to be queried directly, rather
> >>    than iterating over them all
> >>  - the iteration over properties have been moved inside the library, rather than
> >>    exposing a list directly
> >>  - the unused 'flags' parameter was dropped
> >
> > Why pull this apart?
> We'd like to move the libudev API closer to the libsystemd one, and as
> the hwdb stuff is actually completely separate from the rest of
> libudev, it is a nice place to start I thought. The benefit is rather
> minor (consistency of API and improved error handling), but still
> worth-while I think.

That makes sense.

> > Are other applications wanting to use this?
> A couple applications use hwdb directly yes, and in some cases without
> using libudev for anything else.

I maintain one such application, usbutils, that only depends on libudev
for the database, so this will be a nice change for it to make.

> If people start using dbus more in
> place of the userspace-to-userspace udev transport, then I guess we'll
> have more cases of programs using hwdb directly without otherwise
> needing libudev, so having these separate (at least their API, if not
> the actual .so) makes sense I think. There have been requests for
> splitting out hwdb before [0], but I don't think these patches help
> much for what they want (and hwdb really does not make sense in a
> non-Linux setting anyway, so I'm not really convinced by that feature
> request at all).

There have been some requests in Gentoo to split this out as well, so
this will make those users happy.

thanks for doing this.

greg k-h

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