I was wondering if there exists any "do's and don't" guide for resource managers. It would be helpful to know what 
system calls from within a resource manager might block, or make the system unstable, etc. For example, is it OK to call
 MsgSend() to another process from within an _io_open() function of a resource manager (assuming that my resource 
manager is mounted at a specific mount point)? any other gotchas to be aware of? I have seen earlier recommendation of 
browsing through the QNX code of resource managers as a way out - I am working on the license requirements to get access
 to the source code (does any one here have a ballpark of what it might cost?); I was wondering if there is any other 
guide that might be helpful.

thanks,