As some of you might already know, there are now (at least :-) ) two
concurrent approaches to implementing ACPI. I do not think that
concurrently developing them is a good idea, and I hope you all agree on
this. I will summarize the advantages and disadvantages of these solutions
briefly:
The "classic" ACPI4Linux patch: This is a rather huge patchset which
already does some things that do not require the AML VM to work. Its
greatest strength is that it contains much useful code, its greatest
weakness size and complexity. I believe that following this track will
need enlarging the kernel by about 300k before we can even dare to
activate any real features.
A modular approach: This is a solution that is entirely module-based as
opposed to the ACPI4Linux patch which is not modularisable. It should work
on 95% of all PCs without patching the kernel, and on 100% with a 2k sized
patch to memory management. The current concept leaves the effective work
to a userspace daemon, the module itself just registers the interrupts and
reaches the events down to userspace. Its greatest strength is simplicity,
its greatest weakness the fact that ACPI devices need to be initialized by
an ACPI enumerator to work correctly, which would require e.g. the IDE
driver to reinitialize the device while the machine is already up and
running, a thing I would not like.
Both patches will require greater changes to other drivers, such as IDE
and USB later on.
I, personally, would vote for the ACPI4Linux patch because testing is
easier if you play with the hardware at a stage where you cannot do much
damage, but other people, including Max Berger, who is the "kernel guy" of
the project (I'm more into userland code) think different on this issue
[Max, Andy, I think it would be good to post something more about the
module here].
We need to make a decision soon, and we would like to have your opinion.
Simon
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