Detect io_uring support on your machine / docker image etc.

gistfile1.txt

Linux command-line:
1. uname -r # expect 5 and above
2. grep io_uring_setup /proc/kallsyms # expect 2 lines
3. gcc test_io_uring.c -o test_io_uring && ./test_io_uring

```C
// test_io_uring.c

#include <stdio.h>
#include <errno.h>
#include <linux/io_uring.h>
#include <stddef.h>
#include <sys/syscall.h>
#include <unistd.h>

int main(int argc, char **argv) {
  if (syscall(__NR_io_uring_register, 0, IORING_UNREGISTER_BUFFERS, NULL, 0) && errno == ENOSYS) {
    printf("%s", "nope\n");
    return -1;
  } else {
    printf("%s", "yep\n");
    return 0;
  }
}

```