Re: [PATCH v3 5/5] mm: enable CONFIG_MOVABLE_NODE on powerpc

[Reza Arbab]

On Tue, Sep 27, 2016 at 07:15:41AM +1000, Benjamin Herrenschmidt wrote:
> What is that business with a command line argument ? Do that mean that
> we'll need some magic command line argument to properly handle LPC memory
> on CAPI devices or GPUs ? If yes that's bad ... kernel arguments should
> be a last resort.

Well, movable_node is just a boolean, meaning "allow nodes which contain 
only movable memory". It's _not_ like "movable_node=10,13-15,17", if 
that's what you were thinking.

> We should have all the information we need from the device-tree.
>
> Note also that we shouldn't need to create those nodes at boot time,
> we need to add the ability to create the whole thing at runtime, we may know
> that there's an NPU with an LPC window in the system but we won't know if it's
> used until it is and for CAPI we just simply don't know until some PCI device
> gets turned into CAPI mode and starts claiming LPC memory...

Yes, this is what is planned for, if I'm understanding you correctly.

In the dt, the PCI device node has a phandle pointing to the memory 
node. The memory node describes the window into which we can hotplug at 
runtime.

--
Reza Arbab