On 25/06/15 17:04, Jude Nelson wrote:
Hey everyone,
After a longer-than-expected development cycle, I have the latest news
for vdev.
The TL;DR is that vdev has gained enough infrastructure to generate the
information that normally gets put in /run/udev. This is important for
most libudev clients, because this information gets used to detect and
enumerate hardware. It's the way the X server detects input devices via
udev, for example.
This is still being heavily tested, and is not complete, but I am please
to report that:
* vdev now tracks device properties and device tags, under
/dev/metadata/$DEVPATH/properties and /dev/metadata/$DEVPATH/tags/,
respectively. They are added by shell library subroutines available to
vdev's helpers (in subr.sh).
* vdev now uses the same hardware database as udev to report
human-curated hardware properties (such as human-readable vendor
strings). To keep things simple, vdev comes with a script that
generates a squashfs filesystem image from the *.hwdb files installed to
/lib/udev/hwdb.d and /etc/udev/hwdb.d. This is our alternative to
systemd's/udevd's mmap()-able on-disk hwdb trie. The filesystem image
itself gets mounted to /dev/metadata/hwdb by the pre-seed script, and
vdev now comes with a helper tool (hwdb.sh) that can use a combination
of a modalias string, a devpath, a subsystem path, and some sysfs
information to look up the device properties.
* vdev now comes with a "udev-compat.sh" helper script that reads vdev's
/dev/metadata/ directory and hardware database in order to generate
/dev/metadata/udev, which is meant to be symlinked to /run/udev. This
lets the udev_enumerate API detect and enumerate devices by tags and
properties. It is important to emphasize that this helper is logically
isolated from the rest of vdev--vdev gets along just fine without it
(since all udev-isms are contained by this helper), so if you don't need
/run/udev, you can safely disable this helper script.
* Disk property detection has been significantly improved, and is much
closer to how udev does it (including adding support for querying a
disk's parent device's properties, which is necessary to handle
partitions properly). Thanks to Didier for working with me on this! In
time, it will also work the busybox tools, but I am still working on
getting busybox's blkid to work here (specifically, we need the "-p"
flag to work in order to get low-level partition table information and
filesystem metadata).
There is of course more work to be done on this, but the next big
milestone (my next goal) will be to boot to X with vdevd, without having
to generate an xorg.conf. I have not tried this yet, and I do not
expect it to work as of the latest commit, but I believe that all the
necessary infrastructure is in place to begin the painstaking process of
ensuring that vdev detects enough of the host's devices' properties for
commonly-used libudev clients work as they did with udev. This will
confirm that we generate enough of /run/udev/ for alpha.
Thanks,
Jude
That's awesome new Jude. Thanks to you and all who have been
participating on this project.
Regards,
--
Daniel Reurich
Centurion Computer Technology (2005) Ltd.
021 797 722
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