[Jack-Devel] Port number limitation

[John Rigg]

On Fri, Aug 23, 2019 at 01:36:13PM +0200, Hannes Helmholz wrote:
> 
> On 2019-08-21 22:52, John Rigg wrote:
> > In jack2 (don't know about jack1) PORT_NUM_MAX is set in
> > JackConstants.h. It's currently set to 4096.
> > 
> > There are other numbers in JackConstants.h like DRIVER_PORT_NUM
> > (currently 256 which is too small for multiple MADI cards,
> > for example).
> > 
> > If you can't get enough ports you might have to raise one or
> > more of those numbers and recompile.
> 
> Ahh, thank you for the hint. The wall I was actually running into here
> was PORT_NUM_FOR_CLIENT being 768.
> 
> What is the reasoning for these limits, since just like that they seem
> very arbitrary? But at least there is a known source for the limitations
> now. :)
> 
> Sadly recompiling is certainly not trivial, mostly because I need to
> work with OSX and eventually Windows. Which both are not officially
> supported atm, I believe.
> In case I manage, should it be feasible to raise some of the limits? Or
> what might happen that I will have to look out for?

I'm not a JACK developer, but I think at least some of those limits
are arbitrary. I know of one user on this list who needed to increase
DRIVER_PORT_NUM to accommodate two RME MADI cards, but the limit
hasn't yet been changed in the git source (probably due to lack of
time). Hopefully a developer will chime in with a more knowledgeable
answer.

John