CPU Bi-Endian support of RK3399

[mschulz]

Hello!

According to ARM the Endian support of the ARMv8 CPUs may vary depending on architecture/model/manufacturer. Therefore I would like to learn whether the RK3399 does support big-endian mode of operation before I decide to order that board. I have written a small test code (32bit ARM!):

Code:

#include <stdio.h>

int main(int argc, char**argv)
{
   (void)argc; (void)argv;

   int tmp = 0;

   printf("Trying to switch endianess\n");

   asm volatile("setend be; str %0, %1; setend le"::"r"(0xdeadbeef),"m"(tmp));

   printf("Value in tmp is %08x, written was %08x\n", tmp, 0xdeadbeef);

   return 0;
}

The code does nothing extraordinary, it just switches the CPU mode to BE, stores variable in memory and switches back to LE, which is most likely the default mode on RK3399. I would like someone to compile this code in 32bit mode and test. There, three things can happen:
1. The "setend" instruction is obsolete and CPU is told to throw an exception on that instruction. In that case sigsegv is thrown and program ends without any output on the console.
2. The "setend" instruction is executed but the CPU does not support BE mode. In that case "Value in tmp is deadbeef, written was deadbeef" will show on the console
3. The "setend" instruction is executed and the CPU supports BE mode. In that case "Value in tmp is efbeadde, written was deadbeef" will show on the console.

Thanks for the help.