From: David Given <dg@cowlark.com>
To: ELKS <linux-8086@vger.kernel.org>
Subject: Fwd: New GCC compiler for 8086 cpu's
Date: Wed, 21 Jun 2017 00:46:14 +0200 [thread overview]
Message-ID: <CALgV52j3dC_hiUbAkJW3AuUFWHbvqbsyKGxZ3sJAeb20o1Vm7Q@mail.gmail.com> (raw)
In-Reply-To: <CALgV52iFRay4y8dYrP0ZGnF2JQJi2h7c=QnSsDniv72azmFPbA@mail.gmail.com>
Unfortunately C doesn't distinguish between pointers to objects in the
heap and pointers to objects on the stack. Consider this:
{
int buffer[256];
int* pointer = buffer; // pointer points to stack frame
pointer = malloc(256*sizeof(int)); // now it points to heap
return buffer[0]; // so the same instruction here needs to be able
to cope with either
}
Vanilla C has two address spaces --- code and data. You're not allowed
to (portably) turn one to the other, so they can live in different
segments. But the stack and the heap are defined to be in the same
address space, and pointers to them have to be interchangeable. So
they need to live in the same segment.
--
┌─── http://www.cowlark.com ───
│ "I have always wished for my computer to be as easy to use as my
│ telephone; my wish has come true because I can no longer figure out
│ how to use my telephone." --- Bjarne Stroustrup
prev parent reply other threads:[~2017-06-20 22:46 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-14 0:08 New GCC compiler for 8086 cpu's Juan Perez-Sanchez
2017-06-14 6:47 ` Tom
2017-06-14 19:53 ` Juan Perez-Sanchez
2017-06-15 10:19 ` Edoardo
2017-06-15 22:53 ` Juan Perez-Sanchez
2017-06-16 13:33 ` David O'Shea
2017-06-16 18:57 ` Juan Perez-Sanchez
2017-06-19 3:58 ` David O'Shea
2017-06-19 6:58 ` Georg Potthast
2017-06-19 9:15 ` David O'Shea
2017-06-19 19:36 ` Juan Perez-Sanchez
2017-06-19 13:16 ` Alan Cox
2017-06-19 13:43 ` Alan Cox
2017-06-19 19:57 ` Juan Perez-Sanchez
2017-06-19 20:55 ` Alan Cox
2017-06-19 22:53 ` Juan Perez-Sanchez
2017-06-20 11:37 ` Alan Cox
2017-06-20 21:57 ` Juan Perez-Sanchez
[not found] ` <CALgV52iFRay4y8dYrP0ZGnF2JQJi2h7c=QnSsDniv72azmFPbA@mail.gmail.com>
2017-06-20 22:46 ` David Given [this message]
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