I'm trying to do exactly the same thing as Gaurav and I found this thread.
First, I ran into the same problem as Gaurav that the beaglebone bricked on
boot with FDT_ERR_BADOVERLAY. The problem was I put the "reserved-memory"
section in my overlay dts, which the overlay system doesn't like.
I moved that to a fragment, and now it boots and there's a reserved-memory
section in /sys/firmware, but looking at dmesg and /proc, I don't think it
actually reserved any memory.
fragment@6 {
target = <&ocp>;
__overlay__ {
reserved-memory {
#address-cells = <1>;
#size-cells = <1>;
ranges;
pruadc_reserved: pruadc_reserved@0x9ffc0000 {
reg = <0x9ffc0000 0x00040000>;
no-map;
status = "okay";
};
};
};
};
So, my question is: how do I get this fragment to actually reserve a chunk
of memory? I just guessed at the target "ocp", so that may be wrong.
(My underlying goal is to allocate a chunk of RAM to share between the ARM
and the PRU; the built-in shared RAM is a bit too small. It seems that the
TIDA01555 <https://git.ti.com/apps/tida01555/> project does just what I
(and presumably Gaurav) want, if I can get it to work.)
Ken
On Tuesday, October 9, 2018 at 6:55:28 PM UTC-7, RobertCNelson wrote:
>
> On Tue, Oct 9, 2018 at 5:58 PM GS <[email protected] <javascript:>>
> wrote:
> >
> > Thanks for the suggestion, Robert.
> > I have attached the complete output. The relevant section is pasted
> here:
> >
> > uboot_overlays: loading /lib/firmware/MEM.dtbo ...
> > 418 bytes read in 94 ms (3.9 KiB/s)
> > failed on fdt_overlay_apply(): FDT_ERR_BADOVERLAY
> >
> > Not exactly sure what it means.
>
> it means, error, bad overlay...
>
> Which means it didn't do the overlay syntax..
>
> We have lots of examples here:
>
> https://github.com/beagleboard/bb.org-overlays/tree/master/src/arm
>
> what's your actual overlay dts file look like?
>
> You need:
>
> /plugin/;
>
> fragment@0 {'s
>
> target = <&xyz>; or target-path="/";
>
> and
>
> __overlay__ {
>
> finally built with "-@"
>
> Regards,
>
> --
> Robert Nelson
> https://rcn-ee.com/
>
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