Open Firmware available after kernel is running?

[Justin Hibbits]

On Thu, 18 Oct 2012 12:27:51 -0700
Rob Ballantyne <robballantyne3 at gmail.com> wrote:

> Hi All,
> 
>   I was wondering if the Open Firmware client interface is available
> after the kernel is booted.
> 
>   For example, could I write a kernel module that accessed Open
> Firmware via the client interface?  I'm supposing that there is likely
> a static variable that points to the client interface that is stashed
> there in early startup -- I understand open firmware passes it's own
> address to the client program on the stack.  However, I'm also
> guessing that the kernel may have taken completely over the machine in
> a way that doesn't permit access to the OF client interface.
> 
>   It appears that ~/sys/powerpc/aim/locore64.S stashes the entry point
> for OF in openfirmware_entry - is this still usable after the system
> is up and running?
> 
>   Thanks,
> 
> Rob

Hi Rob,

Yes, Open Firmware is available after bootup.  sys/dev/openfirm
provides a device interface for Open Firmware that you can look at as a
reference.

I'm hoping to eventually be able to quiesce Open Firmware on PowerPC,
as it may be necessary for certain features (speed change on PowerBooks
and sleep) to work.  This is still a ways off though.

- Justin