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

[Arne Vajhøj]

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 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.

So no need for any assembler to make system calls.

Arne