Hello, Am 09.11.2010 17:47, schrieb Johannes Meixner: > > Hello, > > On Nov 9 09:02 m. allan noah wrote: >> Wilhelm- This looks very promising! >> >> On Sat, Nov 6, 2010 at 3:18 PM, Wilhelm <wilhelm.meier at fh-kl.de> wrote: >>> FYI: >>> >>> scanbd (scanner button daemon) can be used in such a case: >>> >>> 1) scanbd uses hal dbus-interface ... > > If it really needs HAL, it is probably not very promising > because HAL is meanwhile deprecated.
yes, I know that! But its not scanbd's fault: all (desktop or not) applications need some kind of HW-notification. For scanbd it's already there: send a signal and it will look for new devices (not via hal, via libsane!). And that is the only purpose libhal is used for! If hal isn't available, that dowsn't hurt: write a udev-rule to send a signal to scanbd (or restart it ...) Bottom line: scanbd may use libhal/dbus, but if hal isn't available, it does not hurt: the only consequence is, that newly plugged scanners aren't instantly detected. Then you can send a signal or restart it via udev. > > See for example > http://en.wikipedia.org/wiki/HAL_%28software%29 > ---------------------------------------------------------------- > As of 2009, distributions such as Ubuntu, Debian, and Fedora, > and projects such as GNOME and X.org are in the process > of deprecating HAL > ... > Initially a new daemon DeviceKit was planned to replace > certain aspects of HAL, but in March 2009, DeviceKit was > deprecated in favor of adding the same code to > udev as a package: udev-extras > ---------------------------------------------------------------- > You may follow the links therein. > > Also we (i.e. Novell/openSUSE) are in the same process, see > http://lists.opensuse.org/opensuse-factory/2010-01/msg00055.html > ---------------------------------------------------------------- > Future Development of "hal" has been stopped. > > Right, there is no future release planned. The project is dead > and the functionality replaced by a bunch of other projects. > ... > > What is replacing it? > > udev-extras (merge between DeviceKit and udev) > > There is no udev-extras. It was a temporary solution > and no such package exists anymore. > ---------------------------------------------------------------- > > At least for me the whole stuff does not look very promising: > HAL deprecated -> DeviceKit deprecated -> udev-extras deprecated > > Welcome to the hell of udev, HAL and its various replacements... > > In the end from my point of view only plain udev is what > one can assume that it exists on an end-user's Linux system > but it does not provide a really stable user interface. > > See > http://www.kernel.org/doc/#sys > ---------------------------------------------------------------- > The maintainers of sysfs do not believe in a stable API, and > change userspace-visible elements from release to release. > The rationale is that sysfs exports information from inside > the kernel to outside the kernel (what API doesn't?) and the > kernel internals change, thus sysfs changes to reflect it. > ... > In reality, sysfs is treated as a private API exported for > the use of the "udev" program > ---------------------------------------------------------------- > > You will learn the consequences when you make udev rules. > Those are not really stable (it is luck if they are stable > for some time) so that you may have to adapt them > from kernel release to release so that strictly speaking > a userspace application which needs udev rules depends > on a particular kernel release. > > As far as I found out the root cause seems to be that udev > is actually meant as a kernel internal tool which is > maintained by kernel maintainers so that the udev rules > for kernel internal stuff (in particular for device drivers > in the kernel) are updated and maintained in compliance > to the particular kernel release. > > As far as I know a userspace application which needs udev rules > seems to be currently some kind of misuse of the kernel internal > tool "udev". > > But I am not at all a udev expert so that I could be wrong here. > > > Kind Regards > Johannes Meixner -- Wilhelm
