Request review of device tree documentation

Ben Dooks ben-linux at
Mon Jun 14 16:00:00 EDT 2010

On Sun, Jun 13, 2010 at 11:36:57PM -0600, Grant Likely wrote:
> On Sun, Jun 13, 2010 at 2:29 AM, Benjamin Herrenschmidt
> <benh at> wrote:
> > On Sat, 2010-06-12 at 20:45 -1000, Mitch Bradley wrote:
> >
> >> Either fought or embraced.  To the extent that it is possible to focus
> >> solely on Linux and ARM, one could image doing a good HAL.
> >
> > That will come with a huge amount of comunity resistance sadly, but I
> > can imagine distros liking it.
> >
> > In general, I much prefer having all the necessary native drivers in the
> > kernel, and the device-tree to provide the right representation, and
> > avoid trying to abstract "methods" via a HAL. It's the Linux philosophy
> > as much as possible (even when defeated by ACPI).
> >
> > But if we're going to be forced by vendors into HALs, we can also make
> > sure that whatever they come up with is half reasonable :-)
> I think there is more to be concerned about regarding binary blobs
> than HALs.  Many of the new SoCs require closed binaries to use all
> the hardware right now (graphics cores in particular).
> Board vendors seem to be taking the plunge and modifying the kernel
> rather than trying to create a HAL for driving board specific
> features.

In my view HALs are a bad idea, they constrain you to one calling method
and make it difficult to evolve support in the kernel. I belive it is
part of the reason that we've always tried to avoid a standardised
kernel driver interface.


Q:      What's a light-year?
A:      One-third less calories than a regular year.

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