SCREEN_X_FONT_SERVER causing Xorg segfaults about thinstation

[Doncuppjr]

I wonder if we have Xorg set to no tcp. Then asking it to connect to something via tcp would certainly cause problems.
On Friday, April 4, 2014 8:56 AM, Jens Maus [email protected] wrote:

Today I tried to set a font server via the SCREEN_X_FONT_SERVER option in thinstation.conf.buildtime and found that the Xorg server immediately exists after quickly showing some progress. It exits with an error and automatically shutdown the machine afterwards.
After some investigation and log file checking I found that Xorg was exited with a segfault which might point at some more severe problem within the Xorg port in thinstation.
Here are the relevant portions of the Xorg.log file:
X.Org X Server 1.11.4
Release Date: 2012-01-27
[ 89.600] X Protocol Version 11, Revision 0
[ 89.600] Build Operating System: ThinStation 5.0 Thinstation
[ 89.600] Current Operating System: Linux fwpnuc33 3.10.27TS_SMP #1 SMP PREEMPT Tue Jan 21 20:07:37 UTC 2014 i686
[ 89.600] Kernel command line: initrd=thinstation/initrd video=uvesafb:800x600-16,mtrr:0,ywrap splash=silent,theme:default console=tty1 loglevel=3 LM=3 BOOT_IMAGE=thinstation/vmlinuz
[ 89.600] Build Date: 13 March 2012 04:51:16AM
[ 89.600] Donald A. Cupp Jr.
...
89.601 FontPath set to: tcp/149.220.4.19:7100
...
[ 91.440]
Backtrace:
[ 91.440] 0: Xorg (xorg_backtrace+0x3b) [0x81bc86b]
[ 91.440] 1: Xorg (0x8048000+0x178335) [0x81c0335]
[ 91.440] 2: (vdso) (__kernel_rt_sigreturn+0x0) [0x7778140c]
[ 91.440] 3: Xorg (ProcessWorkQueue+0x30) [0x80795a0]
[ 91.440] 4: Xorg (WaitForSomething+0x6e) [0x81b99fe]
[ 91.440] 5: Xorg (0x8048000+0x2cb7e) [0x8074b7e]
[ 91.440] 6: Xorg (0x8048000+0x1afda) [0x8062fda]
[ 91.440] 7: /lib/libc.so.6 (__libc_start_main+0xe6) [0x77315de6]
[ 91.440] 8: Xorg (0x8048000+0x1abb1) [0x8062bb1]
[ 91.440] Segmentation fault at address (nil)
[ 91.440]
Fatal server error:
[ 91.440] Caught signal 11 (Segmentation fault). Server aborting
[ 91.440]
[ 91.441]
Please consult the ThinStation made by Don Cupp support at http://www.thinstation.org
...
[ 91.493] Server terminated with error (1). Closing log file.
Question is, can you reproduce that problem? Any hints?
—
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[Doncuppjr]

Well, I looked and we do have it set not to listen on tcp, but it should be fine to connect on tcp. I do see that we have ipv6 support built in. Do you have the ipv6 kernel module available for it to load?
On , Don Cupp [email protected] wrote:

I wonder if we have Xorg set to no tcp. Then asking it to connect to something via tcp would certainly cause problems.
On Friday, April 4, 2014 8:56 AM, Jens Maus [email protected] wrote:

Today I tried to set a font server via the SCREEN_X_FONT_SERVER option in thinstation.conf.buildtime and found that the Xorg server immediately exists after quickly showing some progress. It exits with an error and automatically shutdown the machine afterwards.
After some investigation and log file checking I found that Xorg was exited with a segfault which might point at some more severe problem within the Xorg port in thinstation.
Here are the relevant portions of the Xorg.log file:
X.Org X Server 1.11.4
Release Date: 2012-01-27
[ 89.600] X Protocol Version 11, Revision 0
[ 89.600] Build Operating System: ThinStation 5.0 Thinstation
[ 89.600] Current Operating System: Linux fwpnuc33 3.10.27TS_SMP #1 SMP PREEMPT Tue Jan 21 20:07:37 UTC 2014 i686
[ 89.600] Kernel command line: initrd=thinstation/initrd video=uvesafb:800x600-16,mtrr:0,ywrap splash=silent,theme:default console=tty1 loglevel=3 LM=3 BOOT_IMAGE=thinstation/vmlinuz
[ 89.600] Build Date: 13 March 2012 04:51:16AM
[ 89.600] Donald A. Cupp Jr.
...
89.601 FontPath set to: tcp/149.220.4.19:7100
...
[ 91.440]
Backtrace:
[ 91.440] 0: Xorg (xorg_backtrace+0x3b) [0x81bc86b]
[ 91.440] 1: Xorg (0x8048000+0x178335) [0x81c0335]
[ 91.440] 2: (vdso) (__kernel_rt_sigreturn+0x0) [0x7778140c]
[ 91.440] 3: Xorg (ProcessWorkQueue+0x30) [0x80795a0]
[ 91.440] 4: Xorg (WaitForSomething+0x6e) [0x81b99fe]
[ 91.440] 5: Xorg (0x8048000+0x2cb7e) [0x8074b7e]
[ 91.440] 6: Xorg (0x8048000+0x1afda) [0x8062fda]
[ 91.440] 7: /lib/libc.so.6 (__libc_start_main+0xe6) [0x77315de6]
[ 91.440] 8: Xorg (0x8048000+0x1abb1) [0x8062bb1]
[ 91.440] Segmentation fault at address (nil)
[ 91.440]
Fatal server error:
[ 91.440] Caught signal 11 (Segmentation fault). Server aborting
[ 91.440]
[ 91.441]
Please consult the ThinStation made by Don Cupp support at http://www.thinstation.org
...
[ 91.493] Server terminated with error (1). Closing log file.
Question is, can you reproduce that problem? Any hints?
—
Reply to this email directly or view it on GitHub.

[jens-maus]

Just tried to remove the "-nolisten tcp" part in the Xorg server startup and it didn't help at all. Furthermore, I also checked if ipv6 is available and I can at least see that there is no ipv6 kernel module available in thinstation. Or which ipv6 module do you mean? ipv6 itself seems to work fine as it is built in and I can see ipv6 addresses being output in "ip addr show".

Any more suggestions to fix that issue?

[Doncuppjr]

Nothing obvious jumps out at me. You might need to play with some of the options. I would not change the version number though, that is a slippery slope indeed, but do you really need a font server?
On Friday, April 4, 2014 9:16 AM, Jens Maus [email protected] wrote:

Just tried to remove the "-nolisten tcp" part in the Xorg server startup and it didn't help at all. Furthermore, I also checked if ipv6 is available and I can at least see that there is no ipv6 kernel module available in thinstation. Or which ipv6 module do you mean? ipv6 itself seems to work fine as it is built in and I can see ipv6 addresses being output in "ip addr show".
Any more suggestions to fix that issue?
—
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[Doncuppjr]

Maybe the issue lies with fontconfig instead.
On , Don Cupp [email protected] wrote:

Nothing obvious jumps out at me. You might need to play with some of the options. I would not change the version number though, that is a slippery slope indeed, but do you really need a font server?
On Friday, April 4, 2014 9:16 AM, Jens Maus [email protected] wrote:

Just tried to remove the "-nolisten tcp" part in the Xorg server startup and it didn't help at all. Furthermore, I also checked if ipv6 is available and I can at least see that there is no ipv6 kernel module available in thinstation. Or which ipv6 module do you mean? ipv6 itself seems to work fine as it is built in and I can see ipv6 addresses being output in "ip addr show".
Any more suggestions to fix that issue?
—
Reply to this email directly or view it on GitHub.

[Doncuppjr]

You could strace the xerver launch. That would at least tell you what it is looking for.
On Friday, April 4, 2014 9:20 AM, Don Cupp [email protected] wrote:

Maybe the issue lies with fontconfig instead.
On , Don Cupp [email protected] wrote:

Nothing obvious jumps out at me. You might need to play with some of the options. I would not change the version number though, that is a slippery slope indeed, but do you really need a font server?
On Friday, April 4, 2014 9:16 AM, Jens Maus [email protected] wrote:

Just tried to remove the "-nolisten tcp" part in the Xorg server startup and it didn't help at all. Furthermore, I also checked if ipv6 is available and I can at least see that there is no ipv6 kernel module available in thinstation. Or which ipv6 module do you mean? ipv6 itself seems to work fine as it is built in and I can see ipv6 addresses being output in "ip addr show".
Any more suggestions to fix that issue?
—
Reply to this email directly or view it on GitHub.

[jens-maus]

Will do that ASAP. However, are you able to reproduce the problem on your side? And yes, I do need a font server here so I would be very happy to see that functionality being available again.

[Doncuppjr]

I don't really have the resources to create such a lab(time mostly), but I'll keep it in mind as I work on my issues.
On Monday, April 7, 2014 4:56 AM, Jens Maus [email protected] wrote:

Will do that ASAP. However, are you able to reproduce the problem on your side? And yes, I do need a font server here so I would be very happy to see that functionality being available again.
—
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[Thinstation]

Is this still an issue with the new xorg?

[jens-maus]

I have now updated our thinstation repository to 5.2 including the new Xorg 7.7 version and unfortunately this problem is still present. Thus, Xorg still crashes as soon as a font server is supplied. Thus, there must be something severly broken regarding Xorg and thinstation. It would be great if you could test that yourself at some point and see if specifying a font server works for you.

[jens-maus]

This is just an update to let you know that even with the latest master branch of thin station 5.3 Xorg crashes when setting SCREEN_X_FONT_SERVER.

This is the latest backtrace in the Xorg.log:

[    36.452] (EE) Backtrace:
[    36.452] (EE) 0: Xorg (xorg_backtrace+0x4d) [0x81fba2d]
[    36.452] (EE) 1: Xorg (0x8048000+0x1b7c15) [0x81ffc15]
[    36.453] (EE) 2: (vdso) (__kernel_rt_sigreturn+0x0) [0xffffe40c]
[    36.453] (EE) 3: Xorg (ProcessWorkQueue+0x30) [0x807d560]
[    36.453] (EE) 4: Xorg (WaitForSomething+0x73) [0x81f8be3]
[    36.453] (EE) 5: Xorg (0x8048000+0x2febe) [0x8077ebe]
[    36.453] (EE) 6: Xorg (0x8048000+0x34645) [0x807c645]
[    36.453] (EE) 7: Xorg (0x8048000+0x1d62e) [0x806562e]
[    36.453] (EE) 8: /lib/libc.so.6 (__libc_start_main+0xe6) [0x77511d46]
[    36.453] (EE) 9: Xorg (0x8048000+0x1d561) [0x8065561]
[    36.453] (EE) 
[    36.453] (EE) Segmentation fault at address 0x0
[    36.453] (EE) 
Fatal server error:
[    36.453] (EE) Caught signal 11 (Segmentation fault). Server aborting
[    36.453] (EE) 
[    36.453] (EE) 
Please consult the ThinStation made by Don Cupp support 
     at http://www.thinstation.org
 for help. 

[jens-maus]

I have noticed that you were recently trying to fix the X_FONT_SERVER issue in thinstation by the following checkin: a5b3a7d. However, after having tested this checking I have to report that the issue still exists and the X server still aborts with a segfault when a font server is specified.

[Thinstation]

Jens,

I'm trying to understand the total value of working on this problem. Do you
have some very old application that can not be made to use fontconfig/pango
for font selection? The "core font" system that would connect to a server
does not offer on the fly dpi scaling or anti aliasing, and is likely not a
desirable user experience.
On Dec 15, 2014 4:35 AM, "Jens Maus" [email protected] wrote:

I have noticed that you were recently trying to fix the X_FONT_SERVER
issue in thinstation by the following checkin: a5b3a7d
a5b3a7d.
However, after having tested this checking I have to report that the issue
still exists and the X server still aborts with a segfault when a font
server is specified.

—
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#40 (comment)
.

[jens-maus]

Well, our IT department have some centralized X font servers running to supply fonts on-demand for any X11 clients. And it seems some fonts are missing per default and we would like to have our thin clients being connected to the centralized font server just in case some fonts are missing.

[Thinstation]

The "core font" system is largely depricated. I looked into the issue, but
it does not look like the issue is limited to thinstation and may be
related to the xorg server. Others have reported the issue since 1.13,
without any real solution coming along. Generally, it's considered low
priority as fontconfig does a much better job with less administrative
overhead.
On Dec 15, 2014 5:38 AM, "Jens Maus" [email protected] wrote:

Well, our IT department have some centralized X font servers running to
supply fonts on-demand for any X11 clients. And it seems some fonts are
missing per default and we would like to have our thin clients being
connected to the centralized font server just in case some fonts are
missing.

—
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#40 (comment)
.

[jens-maus]

I understand. However, this still IMHO requires a bug report here or upstream in the Xorg bug tracker since crashing the X server with a seg fault should definitely never happen.

[Doncuppjr]

That's true, I'll go see what the xorg people say.

 On Monday, December 15, 2014 5:45 AM, Jens Maus <[email protected]> wrote:

I understand. However, this still IMHO requires a bug report here or upstream in the Xorg bug tracker since crashing the X server with a seg fault should definitely never happen.—
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[Doncuppjr]

So, it appears to be a known issue that xft segfaults with Xinerama. Talking with some of the developers in the xorg irc channel, it became very clear that this is not likely to be fixed. The only real solution I see for us, is to simply stop declaring that we support font servers and make the code ignore any request to use one.