title: strace print asound ioctl
body: <p>my strace tends to confuse some <code>ioctl</code> values (I'm sure that the <code>SNDRV</code> ioctls is not recognized well...)</p>
  
  <p>how I can recognize the right <code>ioctl</code> value?</p>
  
  <p>a little example:</p>
  
  <p><code>$ strace aplay -l</code></p>
  
  <pre><code>...
  fcntl64(4, F_SETFD, FD_CLOEXEC)         = 0
  ioctl(4, UI_DEV_CREATE, 0xbfaa6e74)     = 0
  close(4)                                = 0
  ...
  </code></pre>
  
  <p>that <code>UI_DEV_CREATE</code> is a <code>SNDRV_CTL_IOCTL_CARD_INFO</code></p>
  
  <p>(another example)</p>
  
  <pre><code>ioctl(4, USBDEVFS_CONTROL or USBDEVFS_CONTROL32, 0xbfaa6f94) = 0
  ioctl(4, UI_DEV_CREATE, 0xbfaa71f0)     = 0
  ioctl(4, 0x80045530, 0xbfaa73ac)  
  </code></pre>
  
  <p><code>USBDEVFS_CONTROL</code> is a <code>SNDRV_CTL_IOCTL_PVERSION</code>
  and I really don't know what is the Macro expansion for <code>0x80045530</code>...</p>
  
  <p>thanks :)</p>