[Info-vax] VAX VMS going forward

[Simon Clubley]

On 2020-07-28, John Reagan <xyzzy1959 at gmail.com> wrote:
> On Tuesday, July 28, 2020 at 8:51:46 AM UTC-4, Simon Clubley wrote:
>> On 2020-07-28, Arne Vajhøj <arne at vajhoej.dk> wrote:
>> > On 7/28/2020 8:31 AM, Simon Clubley wrote:
>> >> 
>> >> Only on VMS. This is (mostly) not a significant problem on other
>> >> operating systems because the vast majority of the work is done for
>> >> you by the compiler and linker in those environments after you tell
>> >> the compiler whether you want your code to run with 32-bit or 64-bit
>> >> addresses and other features.
>> >
>> > ????
>> >
>> > On what other platform is it common to pass 64 bit addresses
>> > as 32 bit bit values with implicit values for the remaining bits?
>> >
>> 
>> As you should well know, you simply don't have to worry about this
>> in those environments. My answer above should have been enough for
>> you to understand the point I was making.
>> 
>> You tell the compiler whether you want a 32-bit or 64-bit executable
>> and it, the linker, and OS support libraries takes care of most of
>> the work for you (if not all the work).
>> 
>> I wish it was that simple on VMS.
>> 
>
> We must be working with different compilers.  There is no qualifier or
> setting to tell the compilers to generate 32-bit code or 64-bit code.  The
> code is the same.  You can ask the linker to place it different with
> LINK/SEG=CODE=P2 or =P0.  You can even copy code from P0 into P2 on Alpha,
> Itanium, and x86.  You might have to readjust some relocations but the
> instructions are perfectly fine in either area (the exception is the
> Itanium C++ compiler).

If you read the context for the discussion, you will see I was talking
about compilers in other environments (such as Linux) where such a thing
does exist.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.