I made a helloworld program on RISC-V qemu using the UART using https://popovicu.com/posts/bare-metal-programming-risc-v/ Uros Popovicu’s guide in RISC-V assembly. I was wondering how I could write to the UART using c and RISC-V qemu.
I tried :

#define UART_TX 0x10000000  

void _start() {
    char *str = "Hello, World!n";
    for (int i = 0; str[i] != ''; ++i) {
        *(volatile char*)UART_TX = str[i];
    }

    while (1);
}

I tried compiling the c code :

riscv64-linux-gnu-gcc -S -o hello.s hello.c
riscv64-linux-gnu-as -march=rv64i -mabi=lp64 -o hello.o -c hello.s

to RISC-V and using the same linker file as in popovicu’s example :

 riscv64-linux-gnu-ld -T linker.ld --no-dynamic-linker -m elf64lriscv -static -nostdlib -s -o hello hello.o

using the following linker file (with only some slight modifications) :

ENTRY(_start)

MEMORY {
  dram_space (rwx) : ORIGIN = 0x80000000, LENGTH = 1024
}

SECTIONS {
  .text : {
    hello.o(.text.bios)
  } > dram_space
}

And running it using :

qemu-system-riscv64 -machine virt -bios hello

This results in nothing being print. Is this the correct way to access the UART or does my error lie elsewhere? Thanks in advance.