Sound bug, GUS & select ()

Sound bug, GUS & select ()

Post by Rolf Fokken » Tue, 21 Oct 1997 04:00:00

Some additional information: a conclusion.

The fact that select () says the sound-device wants data, but ioctl ()
saying it doet not, creates very CPU-consuming programs!

I suspect a bug! That is a bug in the kernel or in my software.



Sound bug, GUS & select ()

Post by Rolf Fokken » Tue, 21 Oct 1997 04:00:00

I wrote a piece of software that uses select () to write data to the

With a SB this works Okay: whenever it's the time to write some data to
the Sound Device the select () moves on, allowing the write to be done.

According to the OSS web-manual, before writing the data, the software
should query the device about the amount of space that's available
(ioctl SNDCTL_DSP_GETOSPACE), so the software knows what's the maximum
amount of data that can be written.

Well, what happens with GUS? After select () the kernel sometimes claims
that there's 0 bytes space for new data.

The kernel is version 2.0.30.

What am I doing wrong?


1. Bug in select() and/or sound drivers in Kernel 2.0.36?

I'm running R.H. 5.2 with an ISA AWE SB card. This works well enough.
However, when opening /dev/audio for read and issuing a select call,
the call eventually times out. Of course, there are always plenty of
data when reading from /dev/audio.

Is this corrected somewhere?


Jon Haugsand
  Norwegian Computing Center, <>

  Fax: +47 22697660, Pb 114 Blindern, N-0314 OSLO, Norway

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