Re: [PATCH] Open Firmware device tree virtual filesystem

Segher Boessenkool
2007-01-02T21:40:01Z

>> The kernel doesn't care if one CPU is in OF land while the others
>> are doing other stuff -- well you have to make sure the OF won't
>> try to use a hardware device at the same time as the kernel, true.
>
> That statement alone hides an absolute can of worms btw ;-)

Oh I know. With a sane OF implementation, things will work
out fine though.

>> I'm a bit concerned about the 100kB or so of data duplication
>> (on a *quite big* device tree), and the extra code you need
>> (all changes have to be done to both tree copies). Maybe
>> I shouldn't be worried; still, it's obviously not a great
>> idea to *require* any arch to get and keep a full copy of
>> the tree -- it's wasteful and unnecessary.
>
> Well, big device-trees generally are on big machines with enough memory
> not to care and the only platform I know where the DT can actually
> change over time is IBM pSeries when doing DLPAR, in which case, OF is
> dead, it all happens via magic HV/RTAS calls and the kernel is
> -supposed- to maintain it's own copy and add/remove nodes from it.

You're almost convincing me. I'll sleep on it a night.

Segher