Hi Rob,
On 30-07-25, 08:39, Rob Herring wrote:
> On Wed, Jul 30, 2025 at 4:29 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> > ### Memory Mapping and Reserved Memory Usage
> >
> > The first two patches enhance the reserved-memory subsystem to support attaching
> > struct device`s that do not originate from DT nodes — essential for virtual or
> > dynamically discovered devices like the FF-A or loopback buses.
>
> We support creating devices from reserved-memory nodes.
I didn't know about this.
> Just add a
> compatible which you should do anyways because node names are not
> supposed to be that specific or an ABI.
Yeah, I already knew that the node-names thing isn't going to fly as
you and Krzysztof rightly pointed out. I just wanted inputs from you
guys and so did that as a first implementation to get the discussion
started.
I tried something like this now:
reserved-memory {
#address-cells = <2>;
#size-cells = <2>;
ranges;
rmem@100000000 {
compatible = "restricted-dma-pool", "virtio-msg,loopback";
reg = <0x00000001 0x00000000 0x0 0x00400000>; /* 4 MiB */
};
};
and this works fine. I am adding two compatibles for virtio-msg:
"virtio-msg,loopback" and "virtio-msg,ffa". Yes I will properly
document them in the next version.
With this, we don't need the 2nd patch anymore:
of: reserved-memory: Add of_reserved_mem_lookup_by_name
but still need the 1st one:
of: reserved-memory: Add reserved_mem_device_init()
Thanks.
--
viresh
