Re: Re: Pragmatic Requirements Summary : update

On Sun, 3 Aug 2003, Aryeh M. Friedman wrote:

> > No, you don't.  You need a machanism to access physical memory locations.  
> > For example, "peek" & "poke" in various versions of Microsoft Basic.  I'll 
> > admit you need better mechanisms than those, but still the number of 
> > places that need to access physical memory, even in an OS, is relatively 
> > small.
> 
> 	Except for a personal dislike of giving people real power to right code
> what is your exact problem with direct memory access?

It's a really stupid way to access data.  The vast majority of bugs in C 
code are caused by bad pointers.  Way too many security exploits have been 
discovered that were caused by buffer overflows (again a pointer problem) 
and finally, memory management in C is total crap.  In the Unix world 
people just seem to expect that memory leaks are to be expected.  In fact, 
Apache is deliberately set up so that each process will die after serving 
a configurable number of requests because of problem with memory leaks, 
particularly in the old NCSA web server.

I've been programming for over 30 years.  I've done real time systems,
high reliablility systems, way too much minicomputer assembly language, C
since before the ANSI standards came out and I've seen the same bugs
happen over and over.  In my experience, even when working inside an OS,
being able to access physical memory is only necessary a small fraction of
the time.

When I first started using Perl, the things I liked about it was the 
ability to actually use strings and the ability to easily manipulate 
variable sized lists of data with all the garbage collection "just 
working".  I've been using Ruby for the last year or so and, again, it 
just lets me manipulate data so easily to solve problems.  While those 
languages are not suited for the guts of an OS, they are well suited for 
implimenting a large number of the utilities.

Ok, that's more ranting than I intended, but after seeing the problems 
(including my own mistakes) of using physical memory addresses when all 
you need are dynamic data structures I sort of thought I should speak up.

-- Matt

-- 
From my heart and from my hand, why don't people understand my intention?


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