[comp.arch] Run time code linking

blarson@skat.usc.edu (Bob Larson) (05/01/89)

In article <46500061@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes:
>I want(ed) the ANSI C standard to REQUIRE
>that one be able to access a given object as both data and code.
>I am NOT - read my lips - referring to what is usually called
>"self modifying code", but rather "incremental compilation".

The ANSI C committe has no busniess trying to REQUIRE something that
would REQUIRE modifacation of almost every operating system (ranging
from changing speifactions to major redesigns) to be able to run ANSI
C.  This doesn't even touch the point that it has NO possible portable
use, and is of questionable utility even on fixed platforms.

>I would like to know why some designers would like to prohibit this.
>I can not see ANY reason why it would be desirable to prevent it.

As another feature, it would need to be tested and supported.  This
means it costs real money to people whether they have any use for it
or not.

Currently, almost any hardware CAN support this feature, (involves
data copying in split I/D pdp11, etc) but few operating systems do
explicity support it, so I recomend you try convincing OS designers
(such as the posix committee) that the need for it outways its costs.
After it is universilly implimented in all OSs, getting it in future
language standards should be trivial.

In the mean time, why don't you try something portable, like forking
the existing program development tools to build a new program, then
execute that.
Bob Larson	Arpa: Blarson@Ecla.Usc.Edu	blarson@skat.usc.edu
Uucp: {sdcrdcf,cit-vax}!oberon!skat!blarson
Prime mailing list:	info-prime-request%ais1@ecla.usc.edu
			oberon!ais1!info-prime-request