Re: inconsistency between server and config file?

[Heikki Vatiainen <hessu@cs.tut.fi>]

For some reason your X setup is different from mine. Below is a short 
description about how my X works. I am using the unstable distribution but it 
should be the same for the stable too.

X in Debian is only a small wrapper for the real X servers like XF86_SVGA. 
/etc/X11/Xserver stores configuration information about who can run X
and which server to use. The X binary reads this information and then starts 
the real X server.

There is also Xserver manual page (available with 'man Xserver') but it has 
nothing to do with the /etc/X11/Xserver file. The manual page describes the X 
server in general and it is probably only a coincidence that there is also a 
configuration file with the same name.

I ran 'strace X' as root (needed to be root since X is a setuid binary) and 
it's output shows how /etc/X11/Xserver is used. Here is a snippet from the 
output:

[cut]
open("/etc/X11/Xserver", O_RDONLY)      = 3
fstat(3, {st_mode=0, st_size=0, ...})   = 0
mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
     0x400ae000
read(3, "/usr/X11R6/bin/XF86_SVGA\nConsol"..., 4096) = 245
getuid()                                = 0
execve("/usr/X11R6/bin/XF86_SVGA", ["/usr/X11R6/bin/X"], [/* 16 vars */]) = 0
[cut]

As you can see, X opens /etc/X11/Xserver and reads it's contents. According 
to the documentation it should then verify if I was console user and start up
the real X server. Since I was running X from console the test passed and it 
went on to fire up the real X server, XF86_SVGA.

See also the additional documentation in /usr/doc/xbase.

Here is what ls shows on my system:
% ls -l /usr/X11R6/bin/X
-rwsr-xr-x   1 root     root         4728 Nov  2 03:27 /usr/X11R6/bin/X
% ls -l /usr/X11R6/bin/XF86_SVGA
-rwxr-xr-x   1 root     root      2703004 Nov  2 03:16 
/usr/X11R6/bin/XF86_SVGA
%

I hope this answers your question :)

// Heikki
-- 
Heikki Vatiainen                  * hessu@cs.tut.fi
Tampere University of Technology  * Tampere, Finland















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