[XFree86] X server startup removes shared memory partitions

2003-11-10 Thread Richard L. Kitchen
I am running version 4.3.0 of XFree86 and I have a problem with
the Xserver removing shared memory partitions that belong to other
processes when it starts.

Apparently when I originally wrote my code which uses shared
memory I unwisely choose to use shared memory keys in the
range 1 - 200.

I notice that the Xserver seems to create shm partitions with
key values of 0 and 2 and most likely other values that I haven't
yet gleaned.

If I change the key value to some rather large number my problem
goes away,  i.e. my partition is not marked for deletion by the
server.

My question is: what ranges of shared memory key values are
being used by the Xserver and friends ?  I would like to change
my code to avoid the problem now and in the future.





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Re: [XFree86] X server startup removes shared memory partitions

2003-11-10 Thread Mark Vojkovich
  The Xserver doesn't pick the keys.  The OS does, ie. it allocates
them with IPC_PRIVATE.  You are trying to allocate segments that
have already been allocated by other processes such as the Xserver.  
Are you calling shmget with IPC_CREAT and checking your return values?
If you're not having the OS allocate them for you by passing
IPC_PRIVATE as the key, you'll need to be checking return values.


Mark.

On Mon, 10 Nov 2003, Richard L. Kitchen wrote:

 I am running version 4.3.0 of XFree86 and I have a problem with
 the Xserver removing shared memory partitions that belong to other
 processes when it starts.
 
 Apparently when I originally wrote my code which uses shared
 memory I unwisely choose to use shared memory keys in the
 range 1 - 200.
 
 I notice that the Xserver seems to create shm partitions with
 key values of 0 and 2 and most likely other values that I haven't
 yet gleaned.
 
 If I change the key value to some rather large number my problem
 goes away,  i.e. my partition is not marked for deletion by the
 server.
 
 My question is: what ranges of shared memory key values are
 being used by the Xserver and friends ?  I would like to change
 my code to avoid the problem now and in the future.
 
 
 
 
 
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