How do I beep PC speaker without a console?

PFudd · 08-30-2005, 04:23 PM

Hi...

I have a linux firewall that sits in a closet in a dark forgotten basement. It doesn't have a graphics card, so I've made the console be the serial port.

In a previous project on a different computer, I was able to make the console beep a couple of times at a different frequency when it had successfully booted. Unfortunately, that required a normal vga console to make it work.

If I do "/bin/echo -e \\a > /dev/console", it shows up as data on the serial port.

I've got the pcspkr module loaded, and it shows up in /proc/bus/input/devices, but now what? What device do I have to open and what ioctl do I have to run, or alternatively, what program do I download and run?

Thanks!

PFudd · 08-30-2005, 06:52 PM

After much searching and sending email to the maintainer (Vojtech Pavlik), a solution was found!

Code:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/kd.h>
#include <stdio.h>

#define ERROR (-1)

main() {
  int fd=open("/dev/tty0",O_RDWR|O_NDELAY);

  if (fd<0) {
    perror("/dev/tty0");
    exit(2);
  }

  /* 125 = 125 milliseconds, or 1/8th of a second;
      0x637 is the number of clock cycles in the standard kernel beep */ 
  if (ioctl(fd,KDMKTONE,(125<<16)+0x637) == ERROR) {
    perror("/dev/tty0: ioctl");
    exit(2);
  }

  close(fd);
}

Initially this was tried with /dev/tty and /dev/console, and it didn't work with either of them. Only /dev/tty0 worked, and even that would not have worked if CONFIG_VT was disabled in the kernel configuration.

Many thanks to Vojtech!