From: Roman Suzi <nuser AT rsuzi DOT pgu DOT karelia DOT ru>
Newsgroups: comp.os.msdos.djgpp
Subject: General Protection Fault Interception vs. Stack checks
Date: Mon, 03 Nov 97 17:39:53 +0300
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To: djgpp AT delorie DOT com
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Hi!

It is now clear how to check free stack space:

Eli Zaretskii wrote:
>Here's one version of `_stackavail' function:
>
>static __inline__ int _stackavail(void)
>{
>  extern unsigned __djgpp_stack_limit;
>  unsigned sp;
>  __asm__ __volatile__ ("movl %%esp,%k0\n" : "=r" (sp) : );
>  return (int)(sp - __djgpp_stack_limit);
>}

Thank you! Its better than nothing.

Meanwhile I contacted a person who reported similar problem
(about mmap() )
as me and have not found solution to it yet.

As he stated, sometimes, stack-availability checks are inacceptable due to
their inefficiency and are trusted to the hardware.

HOWEVER:
My posting about Fighting Gen.Prot.Faults
was addressing the question is there any mechanism
in DJGPP to intercept GPEs, caused by stack overflow ?

It seems, there is not any...
Possibly, existing DPMIs are not permitting to
intercept GPF of stack frame.

I think, this GPF interception question could be important to people,
writing interpreters and stack-greedy real-time applications.
So, if someone can enlighten us on the topic,
you are welcome!


Roman.


--
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--  Roman A. Suzi * Petrozavodsk Karelia Russia --
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