OS/2, eCS & ArcaOS - Technical > Hardware

The last nail in OS/2's coffin

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Lars:

--- Quote from: Dave Yeo on January 23, 2024, 05:42:16 pm ---
--- Quote from: Lars on January 23, 2024, 05:18:53 pm ---Correct. Virtualization of OS/2 (and likewise: DOS and Windows 16-bit) will not be possible once x86-S is introduced. Only emulation will be possible (with a huge performance impact, of course).

--- End quote ---

This raises the question of how virtualization works currently with a 64 bit system running 16 bit code. My understanding is that in 64 bit mode, 16 bit software doesn't work.
As for emulation, with JIT compiler, performance can be pretty good. The PowerPC OS/2 was supposed to run DOS/WinOS2 well, as well as some versions of NT such as the Alpha port.
I doubt that anyone will actually do it but possible.

--- End quote ---


--- Quote ---Compatibility mode (sub-mode of IA-32e mode) — Compatibility mode permits most legacy 16-bit and
32-bit applications to run without re-compilation under a 64-bit operating system. For brevity, the compatibility
sub-mode is referred to as compatibility mode in IA-32 architecture. The execution environment of compatibility
mode is the same as described in Section 3.2. Compatibility mode also supports all of the privilege levels
that are supported in 64-bit and protected modes. Legacy applications that run in Virtual 8086 mode or use
hardware task management will not work in this mode.
Compatibility mode is enabled by the operating system (OS) on a code segment basis. This means that a single
64-bit OS can support 64-bit applications running in 64-bit mode and support legacy 32-bit applications (not
recompiled for 64-bits) running in compatibility mode.
Compatibility mode is similar to 32-bit protected mode. Applications access only the first 4 GByte of linearaddress
space. Compatibility mode uses 16-bit and 32-bit address and operand sizes. Like protected mode, this
mode allows applications to access physical memory greater than 4 GByte using PAE (Physical Address Extensions).
--- End quote ---

So, with the existing "IA-32e" architecture, your OS can be running all in 64-bit mode while it can still execute applications containing 32-bit and 16-bit code (and data) segments. Obviously, Virtualbox uses this support to run 16-bit and 32-bit OSes like DOS, Windows 3.x and OS/2.

Once x86-S is introduced, Intel CPUs will no longer support this "compatibility mode".

JTA:
Poked around on other forums, mentioning the X86-S spec, and folks there pointed out some VirtualBox tidbits:

  - old versions of VirtualBox emulated enough of a CPU such that they could run OS/2 when other virtualization products couldn't.
  - newer versions of VirtualBox no longer needed that emulation layer, as they could pass things thru to the CPU directly. But, to this day, VirtualBox still has pieces of QEMU in it.

Most likely, both VirtualBox and QEMU will be able to run OS/2 long after a particular x64-only CPU can't. I'd guess that Intel needs a new line of x64-only CPU's to carry them further into the server ecosystem. But I'd also guess that they'll continue CPU's that support legacy business apps for a long time (lots of money there).

If DOS, an OS that is older than OS/2, can be emulated and survive & thrive to this day, there shouldn't be any reason why OS/2 (all variants) can't be emulated as well, and prosper long into an x64 world. VirtualBox (virtualization) and QEMU (emulation) will get us there.

CPU's might take away a needed "layer of compatibility" on the one hand, but they almost always give back with "speed" on the other hand. Emulation developers do the rest ...

Roderick Klein:

--- Quote from: JTA on January 25, 2024, 01:41:54 pm ---Poked around on other forums, mentioning the X86-S spec, and folks there pointed out some VirtualBox tidbits:

  - old versions of VirtualBox emulated enough of a CPU such that they could run OS/2 when other virtualization products couldn't.
  - newer versions of VirtualBox no longer needed that emulation layer, as they could pass things thru to the CPU directly. But, to this day, VirtualBox still has pieces of QEMU in it.

Most likely, both VirtualBox and QEMU will be able to run OS/2 long after a particular x64-only CPU can't. I'd guess that Intel needs a new line of x64-only CPU's to carry them further into the server ecosystem. But I'd also guess that they'll continue CPU's that support legacy business apps for a long time (lots of money there).

If DOS, an OS that is older than OS/2, can be emulated and survive & thrive to this day, there shouldn't be any reason why OS/2 (all variants) can't be emulated as well, and prosper long into an x64 world. VirtualBox (virtualization) and QEMU (emulation) will get us there.

CPU's might take away a needed "layer of compatibility" on the one hand, but they almost always give back with "speed" on the other hand. Emulation developers do the rest ...

--- End quote ---

Its not that easy virtualization will full x86 emulation.  It has an impact on perfomance.

Roderick

ivan:
Has anyone considered that AMD might not blindly follow Intel down this road?  I see this as an attempt by Intel to gain relevance.

Mentore:

--- Quote from: ivan on January 26, 2024, 01:03:14 am ---Has anyone considered that AMD might not blindly follow Intel down this road?  I see this as an attempt by Intel to gain relevance.

--- End quote ---

This may indeed be a possible scenario, also due to the technical challenges a complete 64 bit transition will create.

That said, I'm fairly sure that the actual x86 architecture will survive for long, before it can be considered a dead horse. Too many installed machines and too much software written for it.
I feel confident OS/2 will survive this generation  8)

Mentore

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