%general-entities; ]> $LastChangedBy$ $Date$ HAL HAL is a hardware abstraction layer, which is a piece of software that provides a view of the various hardware attached to a system. In addition to this, HAL keeps detailed metadata for each piece of hardware and provides hooks such that system and desktop-level software can react to changes in the hardware configuration in order to maintain system policy. The most important goal of HAL is to provide plug-and-play facilities for UNIX-like desktops with focus on providing a rich and extensible description of device characteristics and features. One example of the functionality provided by HAL is when you plug in a USB storage device. HAL can automatically create a mount point in /media and mount the device. Package Information Download (HTTP): Download (FTP): Download MD5 sum: &hal-md5sum; Download size: &hal-size; Estimated disk space required: &hal-buildsize; Estimated build time: &hal-time; HAL Dependencies Required , (see the ), , and Recommended (with a current pci.ids file) and (with a current usb.ids file) Optional , , , , and User Notes: You must create a dedicated user and group before installing the package. Though the default BLFS instructions run the HAL daemon as the root user, a configuration file is installed which has the dedicated user's name hard-coded in it. This causes a confusing message to be generated when starting the D-BUS daemon. Issue the following commands as the root user: groupadd -g 19 haldaemon && useradd -c "HAL Daemon User" -d /dev/null -u 19 \ -g haldaemon -s /bin/false haldaemon Install HAL by running the following commands: ./configure --prefix=/usr \ --sysconfdir=/etc \ --libexecdir=/usr/lib/hal \ --localstatedir=/var && make To test the results, issue make check. Now, as the root user: make install && install -v -m755 -d /var/run/hald --libexecdir=/usr/lib/hal: This parameter forces the installation of libexec files to /usr/lib/hal instead of /usr/libexec. --localstatedir=/var: This parameter forces the creation of the pid file to /var/run/hald instead of /usr/var/run/hald. The program requires several additional packages to be installed before it will run. The list is significant and requires a substantial commitment to install them. It is left up to you to determine if the time and effort spent installing the following packages is worth using the hal-device-manager program. Though the only requirement to run the hal-device-manager program is installing GNOME-Python, the dependency list is staggering. The following list does not include the dependencies already identified in the BLFS book. For example, libgnome already lists GNOME VFS, GConf, etc., so they are not repeated here. Note that some of the dependencies have their own dependencies, which have their own, and so forth and so on. GNOME-Python PyGTK (required) Pycairo (optional) libsvg-cairo (optional) libsvg (required) PyGTK (optional, and circular) Numerical Python (optional) Numerical Python (optional) (required) (optional) (required) PyORBit (optional) (required) The dependency list is designed to start at the bottom and work your way up until the last package to install is GNOME-Python. Note that the dependencies marked as required are required for the package it is listed under. For example, you don't need to install ORBit if you don't plan on installing PyORBit. The minimum packages you could install to support running would be (in this order): , , PyGTK and GNOME-Python. /etc/dbus-1/system.d/hal.conf, /etc/dbus-1/system.d/halusers.conf and /etc/hal/* /etc/dbus-1/system.d/hal.conf /etc/dbus-1/system.d/halusers.conf /etc/hal/* The default setup for HAL is to allow only certain users to invoke methods such as Mount(). These are the root user and the user determined to be at the active console using pam_console. If you are not set up to use and pam_console, create a group that is allowed to invoke HAL methods with the following commands: groupadd -g 61 halusers && cat > /etc/dbus-1/system.d/halusers.conf << "EOF" <!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN" "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd"> <busconfig> <!-- Allow users in the halusers group invoke HAL methods --> <policy group="halusers"> <allow send_interface="org.freedesktop.Hal.Device.SystemPowerManagement"/> <allow send_interface="org.freedesktop.Hal.Device.LaptopPanel"/> <allow send_interface="org.freedesktop.Hal.Device.Volume"/> <allow send_interface="org.freedesktop.Hal.Device.Volume.Crypto"/> </policy> </busconfig> EOF Now add the users you would like to the halusers group to use HAL. Note that these users still need to have appropriate permissions to access the devices that HAL will invoke its methods on. With the above configuration in place, authorized users now have the ability to unmount disk partitions mounted at non-standard locations such as /pub. If you'd like to restrict this policy to only drives which are considered removable or hotpluggable, add the following configuration file as the root user: cat > /etc/hal/fdi/policy/no-fixed-drives.fdi << "EOF" <?xml version="1.0" encoding="UTF-8"?> <!-- -*- SGML -*- --> <!-- Don't allow HAL methods on disks that are not removable or hotpluggable --> <deviceinfo version="0.2"> <device> <match key="@block.storage_device:storage.hotpluggable" bool="false"> <match key="@block.storage_device:storage.removable" bool="false"> <merge key="volume.ignore" type="bool">true</merge> </match> </match> </device> </deviceinfo> EOF HAL only provides the methods such as Mount() to act on hardware. In order to take advantage of these, a HAL event handler such as or Ivman should be installed. HAL will ignore any devices listed in /etc/fstab for the purpose of automounting. You must remove any listings for devices that you would like automounted such as CD-ROMs or USB keys. To automatically start the hald daemon when the system is rebooted, install the /etc/rc.d/init.d/haldaemon bootscript from the package. haldaemon If the system-wide D-BUS daemon was running during the installation of HAL, ensure you stop and restart the D-BUS daemon before attempting to start the hald daemon. make install-haldaemon Installed Programs Installed Libraries Installed Directories hal-device, hal-device-manager, hal-find-by-capability, hal-find-by-property, hal-get-property, hal-set-property, hald and lshal libhal.{so,a} and libhal-storage,{so,a} /etc/hal, /usr/include/hal, /usr/lib/hal, /usr/share/doc/hal-&hal-version;, /usr/share/hal and /var/run/hald Short Descriptions hal-device is used to create, remove or show a HAL device. hal-device hal-device-manager shows a graphical representation of all the devices HAL is aware of. This program requires . Here is a screenshot of hal-device-manager communicating with the HAL daemon and displaying a tree of device objects. The shown properties in the screenshot are for a device object representing a hard disk. hal-device-manager hal-find-by-capability prints the Unique Device Identifiers for HAL device objects of a given capability. hal-find-by-capability hal-find-by-property prints the Unique Device Identifiers for HAL device objects where a given property assumes a given value. hal-find-by-property hal-get-property retrieves a property from a device. hal-get-property hal-set-property attempts to set property for a device. Note that, due to security considerations, it may not be possible to set a property. hal-set-property hald is the HAL daemon program. hald lshal shows all devices and their properties. If the --monitor option is given then the device list and all devices are monitored for changes. lshal libhal.{so,a} contains the API functions required by the HAL programs. libhal.{so,a} libhal-storage.{so,a} contains the API functions required by the HAL storage and volume utility programs. libhal-storage.{so,a}