Re: pmac_nvram problems

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> I'm not sure why alloc_bootmem is used at all (is the nvram larger than
> a couple of pages on any machine? And if it is, should it really be
> cached in RAM?), but I think it should be sufficient to just use kmalloc
> (well, it works for me).

There used to be cases where we used the nvram stuff before kmalloc()
was available. I'll check if this is still the case.
 
> Secondly, this driver misses power management. Having suspended, I
> booted OSX which always resets the boot volume. But after resuming
> linux, nvsetvol(8) still reports 0 as the boot volume because the
> pmac_nvram driver caches the nvram contents. Fixing this would require
> converting the driver to the new model though, I think.

Well... the driver doesn't expect you to boot a different OS while
suspended to disk :)

Regarding caching the data in memory, this is done becaues nvram is
actually a flash on recent machines, and you really want to limit the
number of write cycles to it.

Ben.