Re: can not startx

[Jon TURNEY <jon.turney@dronecode.org.uk>]

On 13/01/2011 10:35, Reinier Post wrote:
> Yaakov (Cygwin/X <yselkowitz <at> users.sourceforge.net> writes: 
>> On 05/01/2010 16:56, eric lin wrote:
>>> this is my /var/log/XWin.0.log
>>> where I think problm cause, fail startx, please help, eric
>>
>> Sigh.  Lets try this again:
>>
>>> Problem reports:       http://cygwin.com/problems.html
>>
>> Yaakov
>> Cygwin/X
> 
> I can't follow the rules, there because I'm posting this from
> 
>   http://post.gmane.org/post.php?group=gmane.os.cygwin.xfree&followup=20508
> 
> which doesn't support attachments.
> 
> My XWin.0.log exhibits the same problem eric lin reported:
> 
>   XKB: Could not invoke xkbcomp
>   [etc.]

Since this has been reported a few times, I've added this to the Cygwin/X FAQ,
[1].

Unfortunately, the X server currently needs to fork() a process to run xkbcomp
as part of it's startup.  If something is interferring with the ability of the
cygwin to do this (e.g. BLOADA or remap issues), then the X server can't start.

[1] http://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-failed-to-compile-keymap

> To check this I replaced xkbcomp with a shell script and indeed,
> it does not get called.  Running as X -logverbose 100 does not
> shed any light on the problem.  Running X or XWin with strace doesn't
> work (strace refuses to run X and on XWin crashes out with access violation,
> I'm on Windows 7).

'strace X' doesn't work because X is a cygwin symlink, which strace, being a
purely windows program, doesn't understand about.

I can reproduce a crash using 'strace XWin'.  The eip value suggests this is
something going boom inside the cygwin DLL.

> --- Process 2116, exception C0000005 at 610C7E86
> 219568  813989 [main] XWin 2116 exception::handle: In cygwin_except_handler exc 0xC0000005 at 0x610C7E86 sp 0x20C920
>    34  814023 [main] XWin 2116 exception::handle: In cygwin_except_handler sig 11 at 0x610C7E86
>    19  814042 [main] XWin 2116 exception::handle: In cygwin_except_handler calling 0x0
>    16  814058 [main] XWin 2116 exception::handle: Exception: STATUS_ACCESS_VIOLATION
>    62  814120 [main] XWin 2116 try_to_debug: debugger_command ''
>   479  814599 [main] XWin 2116 open_stackdumpfile: Dumping stack trace to XWin.exe.stackdump
> --- Process 2116, exception C0000005 at 61026397
> 88607  903206 [main] XWin 2116 exception::handle: In cygwin_except_handler exc 0xC0000005 at 0x61026397 sp 0x20C434
>    49  903255 [main] XWin 2116 exception::handle: In cygwin_except_handler sig 11 at 0x61026397
>    19  903274 [main] XWin 2116 exception::handle: In cygwin_except_handler calling 0x0
>    17  903291 [main] XWin 2116 exception::handle: Exception: STATUS_ACCESS_VIOLATION
>  8266  911557 [main] XWin 2116 exception::handle: Error while dumping state (probably corrupted stack)
> 54526  966083 [main] XWin 2116 _cygtls::inside_kernel: pc 0x61026397, h 0x61000000, inside_kernel 0

> The problem appeared after running a rebaseall and rebooting for a regular
> Windows 7 update.  I haven't made any hardware changes and Cygwin/X was
> running fine yesterday.  After the problem appeared,
> running another erebaseall or updating my Cygwin 1.7 installation
> didn't help.

What arguments did you use to rebaseall?  I seem to recall Windows 7 doesn't
work well with the default ones.

>>> Problem reports:       http://cygwin.com/problems.html

Windows 7 or Windows 7 64bit? Please attach your cygcheck output as requested
by the URL above.

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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