[rescue] VAXstation questions

Dave McGuire mcguire at neurotica.com
Thu May 15 10:56:49 CDT 2003

On Thursday, May 15, 2003, at 06:11 AM, Peter Corlett wrote:
>> On Wednesday, May 14, 2003, at 07:21 AM, Peter Corlett wrote:
> [...]
>>> Object size tells you nothing, really.
>> Object size...the size of the resulting executable...tells you nothing
>> about the instruction set compactness of the target architecture?
> Sorry, I was sloppy in my usage. What I meant was that object size 
> (which
> does relate to instruction density) tells you nothing about the typical
> memory usage of an OS running on that architecture.

   Oh yes yes...I agree with that statement completely.  It does, 
however, tell you about the potency of the instruction set, which is 
the point I was trying to make.

> I'd hazard a guess that VAX Linux (is there such a beast?) would use 
> much
> more memory than VAX VMS.

   Well, Linux boots at least far enough on a VAX to identify some 
hardware and print a startup message, which seems to be enough to 
consider it "ported" to the Linux community. ;)

>> But, within your two examples, while the M68K is a much more "compiler
>> friendly" CISC architecture, I would fully expect GCC to produce 
>> better
>> code (even though GCC generates fairly decent M68K code) on x86 than 
>> M68K
>> because the GCC team has been wearing "x86 blinders" for the past 
>> several
>> years now...targeting the bulk of their optimization efforts at that
>> architecture while letting all the modern architectures rot.
> I think this is probably correct, although I suspect that PPC is also 
> an
> important target these days.

   Agreed...Apple even uses it for OS X.  I'd imagine they're putting 
some pressure (hopefully $$$) on the GCC development team.

>  I note that gcc3.3 does seem to generate much
> better m68k code than earlier versions.

   Does it really?  Wow, that is *cool*.  Especially because I'm going 
to be starting a lot of m68k development this summer. :)


Dave McGuire                "They live deeply, these vagabonds."
St. Petersburg, FL                            -Goro

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