On 01/15/2017 04:44 PM, Andreas Färber wrote:

Am 23.12.2016 um 10:42 schrieb Heinrich Schuchardt:

quoted

it really makes a difference if we write

 	memory@0 {
 		device_type = "memory";
 		linux,usable-memory = <0x0 0x1000000 0x0 0x7f000000>;
 	};

or

 	memory@0 {
 		device_type = "memory";
 		reg = <0x0 0x1000000 0x0 0x7f000000>;
 	};

The second version leads to failure of the Odroid C2.

When I looked at /sys/firmware/fdt I saw this difference:

--- fails
+++ works

        memory@0 {
-               device_type = "memory";
                reg = <0x0 0x0 0x0 0x78000000>;
+               device_type = "memory";
+               linux,usable-memory = <0x0 0x1000000 0x0 0x7f000000>;
        };

I found the following sentence in the NXP forum:
In case you want to overwrite the memory usage passed from u-boot, you
can use "linux,usable-memory".
https://community.nxp.com/thread/382284

The Odroid-C2 is in mainline U-Boot. Please submit a patch to U-Boot
instead of forcing the creation of unnecessary new .dts files onto
everyone due to hardcoded linux,usable-memory properties. In fact, it
already reserves 0x1000000, so it seems you are merely using an older
U-Boot.

http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/mach-meson/board.c;h=f159cbf849f75ab046e6f3a025bbc97c0bcfd59d;hb=HEAD#l39

I would bet that the upper limit is unrelated here.

Regards,
Andreas

Hi Andreas,

I really disagree about relying on any work or properties added by any bootloader here, Amlogic SoCs has
a lot of u-boot version in the field, and the Odroid-C2 is part of this.

Even if Odroid-c2 is in mainline U-Boot or not, the mainline Linux kernel should work using
any U-boot version even with the one provided by Amlogic on their openlinux distribution channel.

Neil