Re: Bootcamp

On 7/3/2025 6:39 PM, Lawrence D'Oliveiro wrote:

On Thu, 3 Jul 2025 10:56:26 -0400, Arne Vajhøj wrote:

5) The idea of emulating one OS on another OS is questionable
     in itself. It is not that difficult to achieve 90-95%
     compatibility. But 100% compatibility is very hard. Because
     the core OS design tend to spill over into
     userland semantics. It is always tricky to emulate *nix
     on VMS and it would be be tricky to emulate VMS on *nix.

 It was always tricky to emulate *nix on proprietary OSes. But emulating
proprietary OSes on Linux does actually work a lot better. Look at WINE,
which has progressed to the point where it can be the basis of a
successful shipping product (the Steam Deck) that lets users run Windows
games without Windows. That works so well, it puts true Windows-based
handheld competitors in the shade.
 That has never been done before. And it’s got to be a more difficult job
than emulating VMS, with its much simpler APIs.

After 31 years of work, then Wine is pretty good. But I don't think
anyone would call it 100% compatible. Which is why many *nix users
still would run real Windows in a VM.
WSL 1 did the other direction. Worked decently, but not 100% compatible
either. So WSL 2 uses a VM to run the real thing.

Getting DCL, image activation, process permanent files,
subprocesses, logicals and symbols working 100% compatible on a
Linux kernel would not be easy. A lot hang on the 4 mode design and
DCL being in S.

 We don’t need to emulate the internals of DCL. We just need to be able to
run users’ command procedures.

The issue is that the internals is reflected in the semantics. It
becomes messy.
Arne