Comment by hot_gril
3 years ago
The creators also would not call virtual machines emulators because they don't translate CPU instructions, which is their narrow criteria for "emulator" that nobody else seems to use.
3 years ago
The creators also would not call virtual machines emulators because they don't translate CPU instructions, which is their narrow criteria for "emulator" that nobody else seems to use.
> is their narrow criteria for "emulator" that nobody else seems to use.
Except the people actually writing or talking about real “emulators”. You know, for things like NES or Gameboy on x86, x86 on WASM, etc.
Sure, you can argue that VMs or Wine are emulators in the broadest sense, but then I could argue that your CPU is an emulator too since it doesn't really runs ASM, and with that very loose meaning almost anything computers related is an emulator. And in practice that's never what people mean when we're talking about an emulator. (Even this thread started with the wrong postulate that WINE must have incurred a performance penalty because the commented believed it was an emulator).
Wine-like things have long been called emulators.
When I was at Interactive Systems Corporation in the mid to late'80s and we were porting System V Release 3 to the 386 for AT&T, we wrote a Wine-like program called i286emul to run 286 System V Release 2 binaries. We and AT&T called it an emulator [1].
Later AT&T and Microsoft and Sun were involved in various projects to merge features from System V R3, BSD, SunOS, and XENIX into System V R4. As part of that they wanted a way to run 286 XENIX binaries, and Microsoft contracted with Interactive for that. We wrote another Wine-like program for that called x286emul. We and Microsoft called it an emulator too [2]
The XENIX emulator led to the stupidest meeting I have ever had to attend. Microsoft said there was an issue with the kernel that could not be resolved over the phone or email. So me and the other guy working on x286emul had to go to Microsoft for a meeting.
A flag needed to be added to the process data structure that would tell the kernel to make some slight changes to a system call or two, due to some differences between System V and XENIX. It was something like XENIX having separate error codes for some things System V rolled into one, or something like that.
The meeting was about how to set/clear that flag. Microsoft wanted to know if we preferred that it be done as a new flag to an existing system call or if a new system call should be added. I looked at the other guy from Interactive and said something like "A flag's fine for me", he said he agreed. We said "flag" to Microsoft, and the meeting ended.
That couldn't have been handled by phone or email?
[1] http://osr507doc.xinuos.com/man/html.C/i286emul.C.html
[2] http://osr507doc.xinuos.com/man/html.C/x286emul.C.html
Things like Wine used to be called emulator, but this usage fell out of fashion a while ago. Now the word “emulator” has been generally refined to mean a (inherently slow) hardware emulator, and most of the compatibility layers explicitly market themselves as not being emulators: “Wine is not an emulator” “Rosetta isn't an emulator”, “x86 compatibility mode is not an emulator”, “virtualization isn't emulation”, and so on.
And even the starting comment on that thread seems to abide by this definition, as it complains about some (imaginary) emulation overhead when using Wine.
Languages changes overtime as usages evolve: when 80286 was released, the French word «baiser» still meant “to kiss” for most people, now it means “to fuck”.
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Yes, those people are writing hardware emulators. Doesn't mean they're the only "real" kind.
As for my Intel CPU, it isn't pretending to be another kind of CPU. Intel makes a leading implementation of x86. Wine follows Microsoft's Windows implementation and translates to Linux calls, and the entire point is so you can run programs intended for Windows on Linux instead. You can get relative about it, but it's not really, they're clearly different. Either way, doesn't support WINE's acronym.
> Yes, those people are writing hardware emulators. Doesn't mean they're the only "real" kind.
They're the only kind that doesn't involve a super broad definition of what the word “emulation” means (so broad that most computing actually fits in this definition).
> As for my Intel CPU, it isn't pretending to be another kind of CPU.
Until one day you realize that you can run an x86 program on a 64 bit CPU (but fortunately, this isn't done through “emulation” proper either).
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So AMD CPU’s are emulators then?
1 reply →