Cygwin 3.6: Supporting 128 POSIX realtime (SIGRTMAX-SIGRTMIN >= 128) signals?

Corinna Vinschen corinna-cygwin@cygwin.com
Mon Mar 3 11:43:02 GMT 2025


On Feb 28 15:36, Lionel Cons via Cygwin wrote:
> We've hit a scalability issue in Cygwin today, the application in
> question ran out of POSIX realtime signals (i.e. SIGRTMIN-SIGRTMAX).
> 
> Could Cygwin support 128 POSIX realtime signals?

Not possible.  sigset_t is an unsigned long, thus we can only support
up to 64 signals.

A change to a bigger sigset_t is an ABI breakage and requires two
different entry points for all functions touching the sigset_t type, one
for the new definition of sigset_t, one for backward compatibility with
existing applications.  This *could* be part of 3.7, but I don't make
any promises.


Corinna


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