Re: stack sizes, Segments

On Thu, 23 Jan 2025 19:45:11 +0000, Scott Lurndal wrote:

mitchalsup@aol.com (MitchAlsup1) writes:

On Thu, 23 Jan 2025 14:00:41 +0000, Scott Lurndal wrote:
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mitchalsup@aol.com (MitchAlsup1) writes:

On Thu, 23 Jan 2025 1:07:02 +0000, Scott Lurndal wrote:
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Do you mean "there is no equivlent *POSIX* function", right?
But I sincerily hope that most Unix-like systems provide such
functionality in system-specific manner. Because it looks usable.

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What would an application (portable or otherwise) use the process
stack base address for?

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As a place to put TLS (or &TLS) on register-starved architectures.

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That's a function of the implementation, not the programmer.

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The compiler needs to know a way of getting TLS in a register starved
ISA.

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The compiler is part of the "implementation".   Very few programmers
work on compilers for register starved architectures (of which few
are still in common use). And very few of them care about the
stack base address.
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    {This is why segmentation bled over into x86-64}

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Well, it gave them a couple scratch registers for use as
kernel and user-mode thread specific region pointers (fs, gs).
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However, I doubt that played a huge factor in AMD keeping what's
left of 80286 segments, they could have just re-used the
encodings for FS and GS for new GPRs and reserved them for
TLS in ABI's for implementations that support threads.

We had long conversations about what to leave in and what to take
(back) out.