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Re: Regression on XP with "Fix OPOST for non-Cygwin pty slaves"
- From: Johannes Schindelin <johannes dot schindelin at gmx dot de>
- To: cygwin at cygwin dot com, Johannes Schindelin <johannes dot schindelin at gmx dot de>, Takashi Yano <takashi dot yano at nifty dot ne dot jp>
- Cc: Corinna Vinschen <corinna-cygwin at cygwin dot com>
- Date: Thu, 28 May 2015 20:14:04 +0200
- Subject: Re: Regression on XP with "Fix OPOST for non-Cygwin pty slaves"
- Authentication-results: sourceware.org; auth=none
- References: <a36a28acdd2deef74569904ab0601c0f at www dot dscho dot org> <20150527125011 dot GI16927 at calimero dot vinschen dot de>
On 2015-05-27 14:50, Corinna Vinschen wrote:
On May 1 16:25, Johannes Schindelin wrote:
Hi Yano & Corinna,
I would like to ask you for help with fixing a regression I am
on XP (and XP only, the problem does not occur with Windows 7 or 8).
be a 32-bit issue, but I cannot currently test on 64-bit XP.
Background: I am the maintainer of Git for Windows and we are hoping
release a new major release Real Soon Now, based on MSys2 (which in
based on Cygwin). To make the user experience a bit better, we want to
users to double-click a "Git Bash" icon that simply launches a small,
non-console MinGW executable which in turn basically sets up the PATH
MSYSTEM environment variables (as required for the MSys2 runtime) and
launches a mintty with a bash inside. Please note that this small
is *not* a console program but a GUI one (-mwindows instead of
that no console window flashes before the mintty window is shown.
Now, this strategy worked well so far, except that I recently found
Bash does not start in XP anymore, instead the mintty process just
waits for a while and after five to ten minutes, the mintty window
with the message:
Failed to fork child process: Resource temporarily unavailable.
DLL rebasing may be required. See 'rebaseall --help'.
(Needless to say, a 'rebaseall' does not fix it.)
This problem does *not* occur if I call mintty from a `.bat` file or
`cmd` -- but as I said, I want to avoid flashing console windows --
also does not happen if I run a mintty from a freshly installed Cygwin
cygwin package version 2.0.1-1) where the shortcut points directly to
`mintty` which is a console application.
This symptom makes me believe that the culprit might be that
somehow expected an attached Win32 Console, and spins in circles when
Now, please note that I do *not* run a regular cygwin1.dll but rather
msys-2.0.dll that I had to patch even more to support users of the
Git for Windows version (which was based on MSys1 and did things like
allowing users to override their home directory using the HOME
Starting with the diff on top of cygwin1.dll's sources, I bisected the
problem down to the commit "Fix OPOST for non-Cygwin pty slaves":
With this commit reverted, on top of the MSys2 and the Git for Windows
patches, the mintty window appears correctly again when launched on
XP via said GUI executable. You can see my current state here:
I would like to ask you for advice how to debug this regression
because I really would like to revert the revert and have a proper
maybe you have an idea how I can fix it directly?
Hmm, this seems to be another fallout from introducing different OPOST
processing (via spearate pipes) for native and Cygwin processes.
Does the patch from https://cygwin.com/ml/cygwin/2015-05/msg00282.html
help, by any chance?
Sadly, my test program still hangs when running with an msys2-runtime
with that patch applied. I cannot say where exactly it hangs, just that
the mintty I call from a GUI program spawns a thread that seems to wait
until something times out.
I won't be able to investigate this during the next week, but I could
put more effort into shedding more light into the problem in the second
or third week of June.
Problem reports: http://cygwin.com/problems.html
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