On 2024-01-03 02:10, Cedric Blancher via Cygwin wrote:
On Mon, 18 Dec 2023 at 18:33, Brian Inglis via Cygwin <cygwin@cygwin.com> wrote:
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:
I am also complaining about performance, but it is NOT "performance in
general": What really sucks is the filesystem inode operations and
file name lookup, e.g. /bin/find&friends are absurdly slow because of
the link emulation and the inflation of syscalls caused by it - just
up to five times more accesses just to handle filename, filename.lnk,
filename.lnk.exe, filename.lnk.bat etc
Other areas have adequate performance, e.g. read/write performance is OK
can you imagine how bad it would be,
compared to Hyper-V, WSL, VirtualBox, etc.
No, qemu is called the "quick emulator", and has more functionality
than just being a hypervisor, like being able to emulate ARM and SPARC
platforms. Even if the x86 hypervisor cannot be used, there is still
lots of functionality.
If there are bugs in the POSIX emulation layer, then those bugs should
be 1) documented and 2) fixed.
There are some functions that are not implemented because they can not be
emulated under Windows, or require far too much work, or code and space in the dll.
Also please do not shoot down package proposals out of the FEAR that
"something" might not work.
Rather knowledge from experience that MS supports certain features in their own
products e.g. WSL/2, Hyper-V and does not provide docs for some of their
proprietary interfaces to allow others to do the same, without e.g. writing
their own drivers to bypass Windows.
As long as you are happy porting a software emulator to build under cygport and
run atop a POSIX layer, let us see how well you can do, by your own measures.
--
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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