hal spec 0.2-pre

David Zeuthen david at fubar.dk
Thu Oct 30 03:30:04 EET 2003


I've compiled most of conclusions from several recent HAL discussion on
this list into a new version of the HAL spec. Find it at


There are major changes in the spec, some of it due to the changes in
D-BUS, some it of because of good ideas vented on this list:

 - Device properties now have types
 - Category and Capabilities properties specified
 - Separation of hardware specific parts into hal_agent.*, meaning that
   the HAL daemon is completely free of any hardware bits
 - Fully documented D-BUS network API
 - Downplay of the device configuration bits - BootProgram and friends
   will probably never be used on Linux
 - Thoughts on how to integrate volume management and other non-generic
   device operations
 - Device Information Files will be XML (not yet specified but should
   be straight-forward)

Personally, I think the spec is a bit clearer now. I'm happy to have
feedback on this - the source for the spec is in hal CVS, module

I'll plan to release HAL 0.2 and a final spec in a few weeks time if
there are no major changes after your review. When that is done, and it
works, the new architecture should enable people to work on both adding
new bus-types (ps2, pcmcia etc.) and writing services such as volume
management without having to touch much of the HAL code. I'll plan to
only provide support for USB, PCI and SCSI (and SCSI, that is storage
volumes from e.g. USB device, only for Linux 2.6).

Oh, I'll also move the current hal CVS module out of the way as a lot of
stuff have changed since 0.1 and I don't know how to remove folders in
CVS. Much stuff have been, and will be, rewritten in the best "always
plan to throw one away - you will anyway" style ;-)

Btw, can someone with appropriate privileges give me access to the HAL
pages in TWiki? My id is DavidZeuthen.


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-                              web:             http://fubar.dk/~david
-    David Zeuthen             pgp key:     http://fubar.dk/pgpkey.asc
-  david(at)fubar.dk           pgp key id:                    b89bab82

    Hofstadter's Law: It always takes longer than you expect, even
    when you take Hofstadter's Law into account.

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