Re: Audio

[" Raymond A. Ingles" <inglesra@frc.com>]

On Tue, 8 Sep 1998, Bart Warmerdam wrote:

> On Tue, Sep 08, 1998 at 06:15:40PM +1200, Michael Beattie wrote:
> > On 7 Sep 1998, Jens Ritter wrote:
> > 
> > > Michael Beattie <mickyb@es.co.nz> writes:
> > > 
> > > > I was going through my .wav file collection, and after a while (250 odd
> > > > playings) bplay died reporting there was "no room left on device". I tried
> > > > starting quake after this... segfault, like I predicted. DMA allocation
> > > > failed.
[...] 
>   The same problems happens to me too. Is occures when my machine is low on
>   physical memory and there seems to be not enough room to allocate the DMA
>   buffer. When you start some big programs (memory consumption) like netscape
>   and terminate them, does that solve it?? It does to me. Error displayed in
>   /var/log/messages is something like "can't allocate DMA buffer" and looks to
>   programs like "can't open device /dev/dsp". If so, please post again.

 Unfortunately, the PC ISA DMA controller can't address memory beyond the
first 16MB. So, when a DMA buffer is requested, the kernel has to find a
continuous chunk of memory that is physically below 16MB. If it can't find
it, too bad.

 Launching a big program like Netscape and exiting will often clear up
some memory if it forces some swapping. There's also a program called
"swapout" from ftape which tries to clear out some DMA-able memory. (Since
ftape uses the floppy controller and DMA, it also needs buffers below
16MB.)

 Sincerely,

 Ray Ingles       (248) 377-7735    ray.ingles@fanucrobotics.com

 "Every question has a simple, easy-to-understand wrong answer."
                        -H. L. Mencken