$ gdb --args /usr/bin/XWin -multiwindow GNU gdb (GDB) (Cygwin 7.10.1-1) 7.10.1 Copyright (C) 2015 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-pc-cygwin". Type "show configuration" for configuration details. For bug reporting instructions, please see: . Find the GDB manual and other documentation resources online at: . For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from /usr/bin/XWin...(no debugging symbols found)...done. (gdb) handle SIGSYS nostop Signal Stop Print Pass to program Description SIGSYS No Yes Yes Bad system call (gdb) r Starting program: /usr/bin/XWin -multiwindow [New Thread 8688.0x129c] [New Thread 8688.0x2b34] [New Thread 8688.0x235c] [New Thread 8688.0x2bac] [New Thread 8688.0x1730] [Thread 8688.0x235c exited with code 0] Welcome to the XWin X Server Vendor: The Cygwin/X Project Release: 1.18.4.0 OS: CYGWIN_NT-10.0 LTFA25932 2.5.2(0.297/5/3) 2016-06-23 14:29 x86_64 OS: Windows 10 [Windows NT 10.0 build 10586] (Win64) Package: version 1.18.4-1 built 2016-07-22 XWin was started with the following command line: /usr/bin/XWin -multiwindow (II) xorg.conf is not supported (II) See http://x.cygwin.com/docs/faq/cygwin-x-faq.html for more information LoadPreferences: /home/050162/.XWinrc not found LoadPreferences: Loading /etc/X11/system.XWinrc LoadPreferences: Done parsing the configuration file... winDetectSupportedEngines - RemoteSession: no [New Thread 8688.0x2568] [Thread 8688.0x2568 exited with code 0] winDetectSupportedEngines - DirectDraw4 installed, allowing ShadowDDNL winDetectSupportedEngines - Returning, supported engines 00000005 [New Thread 8688.0x1cc4] gdb: unknown target exception 0x80000001 at 0x7ffff5797bf4 Program received signal ?, Unknown signal. [Switching to Thread 8688.0x1cc4] 0x00007ffff5797bf4 in ntdll!RtlAcquireSRWLockShared () from /cygdrive/c/WINDOWS/SYSTEM32/ntdll.dll