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Date: Tue, 23 Sep 2025 11:49:48 +0200
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Subject: Re: Why does Cygwin not use MiCloneProcessAddressSpace() for fork()
To: cygwin@cygwin.com
From: Lionel Cons via Cygwin <cygwin@cygwin.com>
Reply-To: Lionel Cons <lionelcons1972@gmail.com>
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On Mon, 22 Sept 2025 at 23:28, Jeremy Drake via Cygwin
<cygwin@cygwin.com> wrote:
>
> On Mon, 22 Sep 2025, Mark Liam Brown via Cygwin wrote:
>
> > Greetings!
> >
> > Why does Cygwin not use MiCloneProcessAddressSpace() for fork()? That
> > function was added for the Windows Services for UNIX, and it still
> > working in Windows 11.
> >
> > Mark
> >
>
> This is a perennial question, and the short answer is that it doesn't play
> well with win32 dlls.  Replies turned up via simple search:
>
> https://cygwin.com/pipermail/cygwin/2016-January/225571.html
> https://cygwin.com/pipermail/cygwin/2018-January/235767.html

Maybe those bugs were fixed in the meantime? UWIN has threads, uses
DLLs (UWIN build DLLs, stock Windows DLLs, 3rd party DLLs, ...) and
obviously has full console support (even tmux works).

I also would be VERY happy to escalate any bugs related to
RtlCloneUserProcess() in Cygwin. Very few things (except proof for
extensions to THE Standard Model) would make me more happy than a
faster (RtlCloneUserProcess() based) fork() in Cygwin.

Lionel

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