Cygwin x86 on Windows 10 ARM64

Corinna Vinschen
Tue Jul 10 13:04:00 GMT 2018

On Jul 10 10:51, David Allsopp wrote:
> I've been trying out the x86 emulation in Microsoft's ARM64 version of
> Windows 10 1803.
> I had two issues with Cygwin x86. The first, which is simple, is that
> Windows doesn't by default create C:\Windows\SysWOW64\drivers\etc which
> causes /etc/postinstall/ to exit with an error all the
> time. I wonder if there's a possible workaround to make that less intrusive?

Try if C:\Windows\Sysnative\drivers\etc works.  That should be the
easiest way to fix the issue in the script.

> The error message implies that it may have computed the wrong directory,
> which it hasn't - it's just that the directory doesn't exist.
> The other is that all Cygwin binaries are emitting the "Could not compute
> FAST_CWD pointer" warning.

Nothing we can do about, unless somebody dives into assembler code on
such a system.  If the code switches to ARM64 early, this could be

As a workaround I pushed a patch to check for running in WOW64 under
ARM64.  The warning is skipped then.  The already existing fallback
code should work most of the time.  Just give the latest developer
snapshot from a try.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat
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