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Re(2): ApplePMU and open source

On Fri, Mar 8, 2002, erik <email@hidden> wrote:

>there can be found some stuff in the freebsd and linux cvs trees, but
>i don't have
>the skills to handle it.

It would be difficult if you don't have access to Apple driver, except
if it's user client allow you to directly send commands to the PMU, but
I don't think that would make much sense to do.

Anyway, the linux/ppc PMU driver can be found in drivers/macintosh/via-pmu.c
of the linux source tree and is up to date in any 2.4.18 or later kernel
if you want to give it a look.

It's annoying for us as well not to have access to Apple's PMU driver source,
but I _think_ I know why they do that. It appears the current PMU driver
contains an updated firmware for the PMU that gets downloaded to it, and for
some reasons, they want "us" to avoid playing with the firmware. I don't think
it's a good way to protect themselves though.

The result is that "alternate" OSes like *BSD or Linux has to either live with
PMU bugs/limitations of the non-up-to-date firmware, or tweak, that is make
a tool that "extracts" the firmware binary from Apple's driver and then does
the update. (The code to send a new firmware to the chip is actually present
in the latest opensourced version in the CVS Attic).

So far, I've decided not to do that as I prefer not taking the risk of
possibly
messing up users machines. Though I would much prefer (even if some kind
of NDA is
required) to know at least what the updated firmare fixes, and have access to
the new driver source to know what routines like "EnableClockspreading"
actually
do ;)

Note that in the case of Linux, it isn't a real problem not to have the
firmware
source, if Apple allow us to do so, we can bundle the binary firmware
along with
our open source driver, this is quite common among some drivers already
to embed
a binary firmware (especially with USB drivers) with proper authorisation from
the vendor without actually having that firmware source code.

Finally, if you have questions about specific PMU things, feel free to ask
me privately, I'll try to answer the best I can.

Regards,
Ben.
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 >Re: ApplePMU and open source (From: erik <email@hidden>)



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