title: Qemu hanging in main system call
body: <p>I was working on the <a href="http://en.wikipedia.org/wiki/Pintos" rel="nofollow noreferrer">Pintos</a> project . And while I was implementing a priority donation mechanism for the proper priority scheduling , QEMU emulator just hung up (I have attached an image and the dump of the pintos is as below ) . I tried debugging and inserting printf statements , but during debugging qemu via a remote host , it again hung up as soon as it entered main . Can anybody tell me how do I troubleshoot all this . Otherwise I will have to reinstall the entire code and qemu and everything in between . </p>
  
  <p>The dump from pintos:</p>
  
  <pre><code>sankalps@ubuntu:~/projects/os_projects/pintos/src$ pintos --gdb -- run alarm-zero
  qemu -hda /tmp/IbpgyXzQhW.dsk -m 4 -net none -serial stdio -s -S
  open /dev/kvm: No such file or directory
  Could not initialize KVM, will disable KVM support
  PiLo hda1
  Loading.........
  Kernel command line: run alarm-zero
  made it till here 
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/VTSzU.png" alt="Pintos emulated on QEMU">Pintos emulated on QEMU</p>