Xref: utzoo comp.os.msdos.programmer:4329 comp.os.os2.programmer:561
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uwm.edu!ogicse!unicorn!kevinj
From: kevinj@unicorn.cc.wwu.edu (Kevin Johnson)
Newsgroups: comp.os.msdos.programmer,comp.os.os2.programmer
Subject: Re: Info on Changing Stacks in protected mode
Message-ID: <1991Mar29.183850.27619@unicorn.cc.wwu.edu>
Date: 29 Mar 91 18:38:50 GMT
References: <1991Mar29.155840.2626@netcom.COM>
Organization: Western Washington University, Bellingham WA.
Lines: 24

resnicks@netcom.COM (Steve Resnick) writes:


>I saw this article in C User's Journal about multi-threaded C using 
>setjmp/longjmp. This was something proposed to me a while ago, and thought
>I'd try and work up my own code. After looking at the code I realized that
>each thread is going to need a new stack. Assembler in hand, I write this
>fairly generic assembler routine which launches the new thread with a new
>stack. Everything works great until I run this under OS/2 rather than MS DOS.
>OS/2 will not let me clear interrupts while changing SS:SP.  My question:
>Is it necessary to disable interrupts while switching stacks in protected 
>mode? 

I always thought it was necessary, and that's how I do it.  Of course, I'm
not an expert on the issue.

>If so, what is the appropriate meathod under OS/2? Is there a call
>to prevent task switching/interrupt processing? Or, should it be implemented
>as part of an IOPL segment? 

Under OS/2, you will want the stack switching code to be in its own segment,
then make that segment have IOPL privileges. 

				--Kevin