Date: Sun, 17 Aug 2003 23:04:30 -0400 (EDT)
From: Daniel Eischen <eischen@vigrid.com>
To: Marcel Moolenaar <marcel@xcllnt.net>
Cc: threads@freebsd.org
Subject: Re: First draft: rewrite of {get|set|swap}context(3)
Message-ID: <Pine.GSO.4.10.10308172303500.29967-100000@pcnet5.pcnet.com>
In-Reply-To: <20030817220623.GA1661@dhcp42.pn.xcllnt.net>
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On Sun, 17 Aug 2003, Marcel Moolenaar wrote: > On Sun, Aug 17, 2003 at 05:12:29PM -0400, Daniel Eischen wrote: > > On Sun, 17 Aug 2003, Marcel Moolenaar wrote: > > > > > Please review the attached patch and let me know to what extend it > > > introduces breakages. It is the result of "aggressive engineering" > > > to provoke comments and further fuel discussion. The reason for this > > > approach is that we currently do not initialize any fields other than > > > the mcontext and sigmask and only partially copyin() and copyout() > > > the contexts (typically only the mcontext and sigmask fields). This > > > generally is very sensitive to breakages, especially when we intro- > > > duce flags or need to use any of the spare fields. > > > > > > getcontext(3): the whole ucontext is zeroed before (partially) filled > > > and we copyout() all of it. This means that uc_link can only > > > be set/defined after calling setcontext(). > > > > This prevents reuse of the same context without resetting > > uc_link after every usage. I don't see any requirement > > by POSIX that uc_link be left intact after getcontext(), > > but it might be worth preserving... It's up to you. > > Yes, it's a tricky issue. I'll begin runtime testing and think about > it some more. I don't want to rush it... > > BTW: I think we need to preserve uc_stack as well. Yes, I think that's a good idea. -- Dan Eischen
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