Date: Tue, 15 Mar 2005 11:35:52 -0800 From: "Michael C. Shultz" <ringworm01@gmail.com> To: Daniel Eischen <deischen@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: threads question Message-ID: <200503151135.53269.ringworm01@gmail.com> In-Reply-To: <Pine.GSO.4.43.0503151312090.12075-100000@sea.ntplx.net> References: <Pine.GSO.4.43.0503151312090.12075-100000@sea.ntplx.net>
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On Tuesday 15 March 2005 10:19 am, Daniel Eischen wrote: > On Tue, 15 Mar 2005, Michael C. Shultz wrote: > > Daniel, sorry to bother you again but I ran into something that is > > either a bug or I am missing a vital piece of information > > somewhere. Here is the situation: > > > > this works perfectly because I moved MGPMrUpgrade into > > the same .c file so it would be a static function: > > > > structProperty* property; > > pthread_t threads[NTHREADS]; > > pthread_create( &threads[0], NULL, zzMGPMrUpgrade, property ); > > > > When I use MGPMrUpgrade from a shared library the function runs > > yet property isn't being passed! > > > > I remember from assembly days that there were some stack tricks to > > be done when making calls to a shared library in order to pass the > > parameters, I forget what they are (been ages since I did assembly > > programming) but anyways it seems like with gcc passing the args > > through the stack to a function in a shared library isn't being > > handled correctly. Am I missing something obvious? > > I don't know. You have to be sure that whatever property > points to stays valid for the life of the thread (or at > least as long as it is used). I have to reply to you through freebsd-hackers@freebsd.org because your blocking verizon's smtp. I just converted everything to static libraries and now pthread_create is working just fine. The answer is probably something like what you just said, scope being lost when making the call to a shared library. Why is it ok going to a static library but not a shared though? In a few days, when there is time, I will write an assembly routine with nasm to use pthread_create and pass my structProperty argument to a shared library with it, this way I can see just exactly what is being passed through the stack. Then hopefully I can find some C/assembly guru who can look at it and teach me how to do it with C. Messing with and examining stacks in C is way beyond my present abilities. (I'm a C newbie) -Mike
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