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Date: Mon, 18 Dec 2023 10:33:21 -0700
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Subject: Re: Qemu packages for Cygwin?
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From: Brian Inglis via Cygwin <cygwin AT cygwin DOT com>
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On 2023-12-18 00:14, Dan Shelton via Cygwin wrote:
> On Mon, 18 Dec 2023 at 07:54, Marco Atzeri via Cygwin wrote:
>> On 18/12/2023 07:42, Dan Shelton via Cygwin wrote:
>>> Does Cygwin come with qemu packages?

>> why should an "Unix Emulation layer" that run in "User Space"
>> trying to run a "Full-system emulation" (https://www.qemu.org/) ?
>> It seems like using square wheels

> Nope. The Qemu packages on LInux have a much more wider functionality,
> and more features, compared to the TUSBTADI "The User Should Be
> Treated As Dumb Idiot" versions on Windows. It absolutely makes sense.

Cygwin has trouble providing some POSIX features under Windows due to its API 
limitations, using "documented" Windows APIs, allowing it to run under ReactOS, 
Wine, and similar emulators, with which there is some interchange.

It does not provide or support much in the way of privileged Unix or Windows 
features or access, except for providing emulation for running daemons as 
services, and some caching of SAM, AD, and process info.

It is totally inadequate as a platform to provide or support any x86 
virtualization or even virtual machine management features, as it can not 
provide access to any machine features that do not have "documented" Windows APIs.
Look at the /proc filesystem emulation limitations for examples of where Windows 
lacks APIs to get information available under Linux.

You complain elsewhere about performance: can you imagine how bad it would be, 
compared to Hyper-V, WSL, VirtualBox, etc.

You can build native Windows Qemu under Cygwin using its native Windows Mingw64 
cross toolchain and libraries, as well as under native Windows Mingw64 and 
Msys2. These provide the best possible performance available under Windows.

The current all volunteer group lingers about the same numbers, with some 
experienced members leaving due to lack of time or interest, and some newer 
members joining and helping out more as they get experience, but they never 
really have enough spare free time to keep up with Windows and POSIX changes, 
address and/or fix issues, improve the emulation, improve POSIX compatibility, 
as well as support much in the way of new features.
-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry


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