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Date: Mon, 3 Mar 2025 12:43:02 +0100
To: cygwin@cygwin.com
Subject: Re: Cygwin 3.6: Supporting 128 POSIX realtime (SIGRTMAX-SIGRTMIN >=
 128) signals?
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From: Corinna Vinschen via Cygwin <cygwin@cygwin.com>
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Cc: Corinna Vinschen <corinna-cygwin@cygwin.com>
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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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