[M3devel] elimination of jmpbuf size from cm3 frontend?

Elmar Stellnberger estellnb at elstel.org
Sun Jul 19 11:10:20 CEST 2015

Am 2015-07-19 um 10:56 schrieb Jay K:
> Merely subtracting the stack pointer isn't correct on all systems.
> At least on NT, stack pages must be touched in order without skipping any,
> for stack overflow exceptions to work correctly.
> There is a high water mark, so it isn't necessarily linear.

Would that mind if the stack exception was generated somewhat
later when the jumpbuf actually becomes accessed?
I would believe no.

> NEWA: alloca is considered kind of dangerous, in that failure
> is difficult to recognize, or not portably recognizable and handlable.

The same stack overflow exception can be generated by any
procedure call so that I do not see why it should be that
dangerous. In the overwhelming majority of cases this should
be handled as gracefully as an extension of the heap on NEW:
simply map a new memory page as long as there is enough
free virtual address space.

> If people can do the work/research/testing for recognizing stack 
> exhaustion
> on a decent set of systems -- Linux, Solaris, FreeBSD, OpenBSD, 
> NetBSD, NT,
> possibly AIX, OpenVMS, Irix, HP-UX -- then this would grain traction 
> in my mind.
As we are planning a new realease I would believe that your new
alterations would become tested shortly.

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