Cygwin/X : display error with latest x-related packages

Cygwin/X : display error with latest x-related packages

[xflr6]

Dear Cygwin/X users and developpers,

I recently experienced a problem with a program using the X window system.
With the latest Cygwin release, the latter program is not able to open the display, 
whereas with previous versions of cygwin (+ the x-window machinery, i.e 
the Cygwin/X installation as described in the installation notes, with xlaunch, 
xinit, xorg-server etc.) (prior to mid-February 2015), it was working correctly.
Other programs using the X window system, such as ghostview for example, 
is working correctly on my installation.
I have seen on the Cygwin/X news that X server and X.Org X11 packages 
have been upgraded to newer versions, and I was wondering if there was 
a known loss of backward compatibility with these fresh versions (even a 
simple change, like in the DISPLAY variable or something like that) ?

Best regards,
xflr6

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re: Cygwin/X : display error with latest x-related packages

[xflr6]

Dear all, 

Concerning my x-related problem, I dig a bit in the x-stuffs, and what I see is the following:
-> Obviously, what doesn't work is the XOpenDisplay function. I do not have the source of 
the program I am using, but it appears that this function is the one that is causing the problem.
I tried to compile and run a dummy example found on the internet using this function and drawing 
a simple box in a window : it's working. So my problem does not seem to be related to the cygwin/X
environment that is installed on my machine.
-> I am wondering if my problem could be caused by: 
- a 32/64bit incompatibility (but as I said before, the program -32b- was working on my 
previous cygwin/X 64b installation, such that I doubt that it is where my problem arise).
- Or if it is a problem of X-library that moved from one directory to another after the upgrade 
of cygwin/X : indeed, the test example that I tried was proposed to be compiled with libraries 
located in /usr/X11R6/lib, whereas the libraries in Cygwin/X are located in /usr/lib/include (And 
I gave this path to the compiler in order to properly compile and run the test example). I was 
wondering if the program that I am using (and for which I have not the sources) have been 
compiled with something like -L/usr/X11R6/lib could still work in a cygwin environment where 
X11 libraries are located in /usr/lib/include. If it is the case, how to make it work ?

Best regards,
xflr6

 
> Dear Cygwin/X users and developpers,
> 
> I recently experienced a problem with a program using the X window system.
> With the latest Cygwin release, the latter program is not able to open the display,
> whereas with previous versions of cygwin (+ the x-window machinery, i.e
> the Cygwin/X installation as described in the installation notes, with xlaunch,
> xinit, xorg-server etc.) (prior to mid-February 2015), it was working correctly.
> Other programs using the X window system, such as ghostview for example,
> is working correctly on my installation.
> I have seen on the Cygwin/X news that X server and X.Org X11 packages
> have been upgraded to newer versions, and I was wondering if there was
> a known loss of backward compatibility with these fresh versions (even a
> simple change, like in the DISPLAY variable or something like that) ?
>
> Best regards,
> xflr6

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Re: Cygwin/X : display error with latest x-related packages

[Jon TURNEY]

On 12/03/2015 15:18, xflr6 wrote:
> I recently experienced a problem with a program using the X window system.
> With the latest Cygwin release, the latter program is not able to open the display,
> whereas with previous versions of cygwin (+ the x-window machinery, i.e
> the Cygwin/X installation as described in the installation notes, with xlaunch,
> xinit, xorg-server etc.) (prior to mid-February 2015), it was working correctly.
> Other programs using the X window system, such as ghostview for example,
> is working correctly on my installation.
> I have seen on the Cygwin/X news that X server and X.Org X11 packages
> have been upgraded to newer versions, and I was wondering if there was
> a known loss of backward compatibility with these fresh versions (even a
> simple change, like in the DISPLAY variable or something like that) ?

Unfortunately, you are rather vague about what program you are running 
and where you are running it, so I can only guess, but there are two 
recent changes which might be the cause of your problems.

1. If the program is running on a remote host and you are trying to 
connect over TCP (rather than using ssh tunnelling, the recommended way 
to do that) you will now need to start the server with the option 
'-listen tcp'.

2. If you are running the program locally and explicitly setting the 
DISPLAY variable yourself, you should be setting it to ":0.0" not 
"localhost:0.0" or "127.0.0.1:0.0" or "::1:0.0" (to avoid trying to use 
a TCP connection)

[1] https://cygwin.com/ml/cygwin-xfree-announce/2015-02/msg00026.html
[2] 
http://x.cygwin.com/docs/ug/using-remote-apps.html#using-remote-apps-telnet
[3] 
http://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-remote-clients-cant-connect
[4] https://cygwin.com/ml/cygwin-xfree/2015-02/msg00051.html

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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Re: Cygwin/X : display error with latest x-related packages

[xflr6]

Dear Mr Turney,

Solution #1 solved my problem: I added this option when launching the X server and 
it works, thank you.
> 1. If the program is running on a remote host and you are trying to
> connect over TCP (rather than using ssh tunnelling, the recommended way
> to do that) you will now need to start the server with the option
> '-listen tcp'.

I saw this on the announcement, but I didn't try it since I was sure not to be in 
that remote case : I was running it locally. Although I do not understand why it 
is now working, anyway, I am now able to do what I needed to.
Sorry for not having tried this solution before asking for help.

Many thanks !
xflr6

On 13/03/2015 14:54, Jon TURNEY wrote:
> On 12/03/2015 15:18, xflr6 wrote:
> > I recently experienced a problem with a program using the X window system.
> > With the latest Cygwin release, the latter program is not able to open the display,
> > whereas with previous versions of cygwin (+ the x-window machinery, i.e
> > the Cygwin/X installation as described in the installation notes, with xlaunch,
> > xinit, xorg-server etc.) (prior to mid-February 2015), it was working correctly.
> > Other programs using the X window system, such as ghostview for example,
> > is working correctly on my installation.
> > I have seen on the Cygwin/X news that X server and X.Org X11 packages
> > have been upgraded to newer versions, and I was wondering if there was
> > a known loss of backward compatibility with these fresh versions (even a
> > simple change, like in the DISPLAY variable or something like that) ?
> 
> Unfortunately, you are rather vague about what program you are running
> and where you are running it, so I can only guess, but there are two
> recent changes which might be the cause of your problems.
> 
> 1. If the program is running on a remote host and you are trying to
> connect over TCP (rather than using ssh tunnelling, the recommended way
> to do that) you will now need to start the server with the option
> '-listen tcp'.
> 
> 2. If you are running the program locally and explicitly setting the
> DISPLAY variable yourself, you should be setting it to ":0.0" not
> "localhost:0.0" or "127.0.0.1:0.0" or "::1:0.0" (to avoid trying to use
> a TCP connection)
>

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