Hi,

In QNX 6.3.0SP3 I would like to implement forwarding of large data block read from socket into a write() call over QNet 
to another node (the transfer MUST be performed with a single write). To avoid allocating large memory block on the 
forwarder node I would be eager to implement "read on demand" schema.
For example, having input data amount of NxM bytes, consider setting up I/O vector with with M pointers to a 
inaccessible memory blocks of N bytes each and calling writev(). Then, when kernel attempts to read from memory and 
segmentation fault occurs, the program catches the SIGSEGV remaps the memory to allow access, reads the block from 
socket and exits the signal handler to retry the operation.
Could that be theoretically possible in QNX architecture?