[Info-vax] The (now lost) future of Alpha.

[invalid]

On 2018-08-02, Arne Vajhøj <arne at vajhoej.dk> wrote:
> On 8/1/2018 3:16 PM, invalid wrote:
>> To answer your point elsewhere that you're hearing from other sources
>> DB/2 is written in C: if you can't build a compiler framework due to
>> differences in *versions* of Linux, imagine how dumb it is to suggest it
>> would be easy or even reasonable to port DB/2 written in C on a mainframe
>> (which it is not, to the best of my knowledge) to other completely
>> dissimilar platforms.
>
> Well - that strategy is used successfully by thousands and thousands
> of applications to support very dissimilar platforms.
>
>> I don't work with DB/2 so I don't know. But I listened in on a meeting
>> recently with a guy who does work with DB/2 every day and has for a few
>> decades. He works in a vendor software DB/2 utilities team. The question of
>> whether DB/2 is written in C came up. This guy told us, from the dumps he
>> has seen he has no evidence DB/2 has any significant amount of code in C. He
>> said he has not seen any evidence at all, but of course he realizes he may
>> have missed something and does not see everything. So he doesn't rule out
>> there might be some C, but as far as he has seen there is not any. This
>> discussion is entirely about DB/2 running on z/OS. I don't know and I don't
>> care about DB/2 for spintel, DB/2 for Linux on Z etc. I'm talking about the
>> real, core DB/2 that started on mainframes.
>
> An anonymous person quoting another anonymous person.

You can judge from my other posts on IBM whether I know what I'm talking
about or not. Or maybe *you* can't, but I suspect other people can.

If I call myself Arne does it help?

The IBM world is full of trade secrets, NDAs, and proprietary info.

>
>> You guys need to understand z/Arch and z/OS are built entirely around
>> assembler. There is *no* direct system interface except in assembler and
>> PL/X. And it is only from around z/OS 1.10 (2.3 just came out and 1.13 was
>> the last of the 1. series) where there was a C compiler capable of running
>> with no runtime and being able to support inline assembler to call systems
>> services since C cannot do it directly. And it is only in the very recent
>> past IBM has started to try to create header files for all the systems
>> services (nothing has been released yet) and we only know it by
>> accident. But it's a huge job and far from complete. When it is done, then
>> it will be physically possible and feasible to write compilers in C. But no
>> reasonable person would suggest they would be willing to take a chance on
>> breaking their enterprise clients applications just so they can say their
>> compilers were written in C.
>
> Well - a compiler can be written in pure C with no system calls at all
> beyond the C RTL.

No, a compiler in the IBM world needs storage and other systems services so
it is OS specific. z/OS is not a POSIX OS although it has POSIX component;
POSIX is not in the picture for normal mainframe languages, not at
compilation time and not at runtime.

> So no need for any assembler to make system calls.

There is if you want to get anything done besides getting control and
returning to the system.