Re: [PATCH] hw: ppc: sam460ex: Disable Ethernet devicetree nodes

[Guenter Roeck]

On 8/16/21 3:11 AM, Philippe Mathieu-Daudé wrote:
> On 8/16/21 7:41 AM, David Gibson wrote:
> > On Sun, Aug 15, 2021 at 07:59:15PM -0700, Guenter Roeck wrote:
> > > IBM EMAC Ethernet controllers are not emulated by qemu. If they are
> > > enabled in devicetree files, they are instantiated in Linux but
> > > obviously won't work. Disable associated devicetree nodes to prevent
> > > unpredictable behavior.
> > >
> > > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> >
> > I'll wait for Zoltan's opinion on this, but this sort of thing is why
> > I was always pretty dubious about qemu *loading* a dtb file, rather
> > than generating a dt internally.
>
> Hmm interesting point.
>
> > > ---
> > >   hw/ppc/sam460ex.c | 8 ++++++++
> > >   1 file changed, 8 insertions(+)
> > >
> > > diff --git a/hw/ppc/sam460ex.c b/hw/ppc/sam460ex.c
> > > index 0737234d66..feb356e625 100644
> > > --- a/hw/ppc/sam460ex.c
> > > +++ b/hw/ppc/sam460ex.c
> > > @@ -194,6 +194,14 @@ static int sam460ex_load_device_tree(hwaddr addr,
> > >           _FDT(fdt_nop_node(fdt, offset));
> > >       }
> > >   
> > > +    /* Ethernet interfaces are not emulated */
> > > +    offset = fdt_node_offset_by_compatible(fdt, -1, "ibm,emac-460ex");
> > > +    while (offset >= 0) {
> > > +        _FDT(fdt_setprop_string(fdt, offset, "status", "disabled"));
> > > +        offset = fdt_node_offset_by_compatible(fdt, offset, "ibm,emac-460ex");
> > > +    }
>
> Oh, I didn't know about appending 'status=disabled'.
>
> FWIW I'm carrying this patch to boot Linux on the raspi4
> (but I prefer your way):

Neat, and excellent idea. I have a similar problem for xlnx-zcu102,
where declaring the affected device as unsupported doesn't work either.
I'll try the same trick there.

Thanks!

Guenter