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crxssi 01-27-2006 05:27 PM

Xterminal + current GTK = segfault
I am busily working on customizing applications on a new Linux server, getting ready for when we will upgrade all the central Linux servers that serve our thin-client desktops, everything going well so far...

Then I decided to try some of the applications running on the new server on one of our "real" NCD or Tektronix Xterminals (instead of from a Linux workstation acting like an Xterminal). Oh no- won't launch, "segmentation fault". I try other applications- same thing. Turns out EVERY application that uses gtk is segfaulting when run from an Xterminal. Old X apps run fine. OO2 works. Even KDE apps run fine. But every GTK app crashes (you name it- gqview, firefox, sylpheed, gtklp, whatever).

So I rounded up a bunch of machines and tested them with the Xterminal launching gtk applications on various other machines:

MDK libgtk Xterminal GTK app launch

2006.0 libgtk+2.0_0-2.8.3-4mdk crash
10.2 libgtk+2.0_0-2.6.4-2mdk no crash
10.1 libgtk+2.0_0-2.2.4-9mdk no crash
10.0 libgtk+2.0_0-2.2.4-10mdk no crash
9.1 libgtk+2.0_0-2.2.1-2mdk no crash
8.2 libgtk+1.2-1.2.10-25mdk no crash

strace isn't much help. Google isn't much help (how many people still even have old Xterminals around). The only thing I could test was to put a Linux workstation in 8 bit color, just to see if GTK apps somehow dropped 8 bit color support- nope, worked fine.

Anyone have any ideas or am I just SOL? I would love for this to be an excuse to get rid of the remaining Xterminals but that is a lot of $, considering I still have 47 of them in active use! Thanks

scott_R 01-27-2006 07:14 PM

Yes, this is a fairly new problem with GTK 2.8, because they opted to go ahead with the Cairo improvements, and work on Xterminal problems later (the idea being that the improvements to the majority were worth the temporary headache to a handful of users, especially as those users generally have more IT knowledge and the ability, patience and skill to work through the problems until they got back to fixing it. Basically, it's a problem with RENDER extensions.

That said, I only know what I read off a number of lists. If you want to explore further, I googled:

cairo +gtk +"x terminal"

It sounds like they were under some pressure to release 2.8, and my guess is maybe they wanted to know how many people needed GTK to work with these terminals, and this is one way to get some feedback. If possible, you might simply want to revert back to an older GTK, or see if they've addressed the situation in their current development tree. Granted, that might mean working with a less stable branch, but if you need the newer version to use a certain piece of software, you may have no option.

Of course, it wouldn't hurt to drop the developers a line asking how long till they get it working again, if for no better reason than to remind them that it's still something people want.

crxssi 01-28-2006 09:18 AM

Thank you so much for your reply. Now I know I am not crazy! I, too, suspected it was due to an Xserver extension, although I didn't know which one or why nor did I really have any way to test that.

It seems odd they would knowingly release something that would break EVERY application for those using Xservers/Xterminals that don't support Xrender!

Well, I will research it some more and try to figure out my options. I now have too much time/energy invested it the current applications to go backwards.

crxssi 01-28-2006 07:58 PM

I am going to cross post some information that is circulating in my LUG on the topic, just incase it is useful to others facing the same problem:
On Sat, 28 Jan 2006 13:08:38 -0500
Charles wrote:

> Sat, 28 Jan 2006 @ 09:48 -0500, Mark A. Davis said:
> > It seems odd they would knowingly release something that would break
> > EVERY application for those using Xservers/Xterminals that don't
> > support Xrender!
> Given their history, it doesn't seem that odd to me.
> I think we can count on Xorg keeping remote sessions working with the X
> extensions and hopefully having graceful degradation for when support is
> absent.
> However, some Gnome people have repeatedly said they really don't care
> about remote X any more, and I suspect a lot of KDE and general app
> writers don't either.

That is truly scary. The whole foundation of X has been transparency.
Without it, the X protocol loses perhaps its most important advantage over
just about every other graphical system.

It does seem sometimes that new programmers completely forget that there
is a whole world of different people using applications in various
different ways. And thin clients are a tremendously powerful, although
often overlooked and underused, part of that world.
On Sat, 28 Jan 2006 15:16:02 -0500
Adam wrote:

> I think that's got a lot to do with the apparent vast majority of
> developers focusing on single-user desktop experiences :)

I agree completely. This kind of thing would never happen even 5 years

> Does any of the new stuff like Beagle or whatever work with more than
> one user running at the same time?

Not quite sure, but if programs like Evolution are any indication, the
answer might be "no". I fought Evolution hard, trying to make it
thin-client and centrally-admined friendly and lost.... switching my
efforts to Sylpheed and WebCalendar (which has worked out fine, afterall).

I have noticed that developers often get sloppy and start programming
making to many assumptions about the power, type, or structure of the
system(s) that it will be run on. It is what made so many MS-Windows-type
programs so incredibly weak and inflexible, and later caused developers a
great deal of problem when they realized that being connected, networked,
and at least pseudo multi-user was important, afterall. Such multiuser,
flexible applications are much more difficult to program.

There have been times I have been amazed that I could display and use very
complex, modern applications, like GIMP or OO2 on very old Xservers and
Xterminals. But to see KDE applications succeed and GTK applications fail
is the last thing I would have expected

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