Message-ID: <4B02AD36.7080408@cs.umass.edu>
Date: Tue, 17 Nov 2009 09:03:34 -0500
From: Eliot Moss <moss AT cs DOT umass DOT edu>
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Subject: What about adding support for sigcontext
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Dear cygwin list --

For some time I've thought about the possibility of adding support for
sigcontext to cygwin -- it would allow (among other things) porting of the
JikesRVM open source Java VM to cygwin, thus making it available to Windows
users.

sigcontext presents more or less complete non-privileged machine state to
signal handlers on demand, and if properly done, allows the handler to change
that state and resume with the changed state. (Caveat utilor, of course, but
in JikesRVM they use it to "fake" calls to exception throwing routines when
certain signals happen; this requires adjusting the PC and some of the
registers.)

"Interesting" difficulties here include the fact that various x86 family
processors have different state.  However, an initially useful implementation
may not need to present all of the state or support changing all of it.

Does anyone feel a degree of ownership or responsibility for the signals and
signal handling part of cygwin?  I'm not asking someone else to take on the
task, but am considering it myself, and want to coordinate, and obtain
guidance and education about modifying cygwin generally so as to contribute
back, and about this part of the system in particular.

As Corinna has pointed out to me, this would NOT be headed for 1.7.1. In fact,
I have no idea when I would have time to work on it. I am at the stage of
trying to figure out how hard and how large a task it is :-) ...

So, please respond if you can help me figure that out or if you have a
particular opinion about this ...

Regards -- Eliot Moss
==============================================================================
J. Eliot B. Moss, Professor               http://www.cs.umass.edu/~moss    www
Director, Arch. and Lang. Impl. Lab.      +1-413-545-4206                voice
Department of Computer Science            +1-413-695-4226                 cell
140 Governor's Drive, Room 372            +1-413-545-1249                  fax
University of Massachusetts at Amherst    moss AT cs DOT umass DOT edu              email
Amherst, MA  01003-9264  USA              +1-413-545-2746 Laurie Downey  sec'y
==============================================================================

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