Hakim <firstname.lastname@example.org> wrote:
So, back to why threads? Why are you trying to use threads? What problem
you trying to solve, that you think threading will help with?
I have a QNX6 driver that I need to port to QNX4. QNX6 driver uses pthread
stuff, so the equivalent I found is _beginthread_endthread etc.
Ah, back-porting a QNX6 driver. Hm.
QNX6 has some nice things, like interchangeability of threads for QNX
IPC, i.e. if thread 1 in a process receives a message, then thread 3
could reply to it, or vice versa. QNX 4 does not have this. And, most
drivers work (at least to some extent) at the QNX message level.
QNX4’s threads aren’t really threads – they are two seperate processes
that share the same code and data. This results in very different
I don’t know exactly how your QNX 6 driver is structured, but I can
see two main ways I’d suggest for porting it back to QNX4:
do it all single threaded in one process. Use a Receive() as a
common blocking point for both proxies from interrupt handlers and
messages from clients. Make sure that nowhere in your code do you
spend too much (based on hw latencies) blocked or doing something,
so you can get back to that Receive() loop.
do it as 2 processes. Put the hw handling in one process, and the
client handling in another process. Use shared memory between the
two process, with semaphores for locking, and proxies for wakeup.
Everything exchanged as “global” data between the threads in the
QNX6 driver would be stuck in the shared memory between the QNX4
If this driver was a resource manager, then porting to an I/O
manager framework will be a whole different issue. It is a lot
trickier to do one under QNX4 – we made it a lot easier under
So, on the ENOMEM – first are you out of system memory? If you are, then
that would explain it.
The system has 192MB system memory, very minimum service is loaded, I can
find the free memory but I’m sure it has lots of MB.
Yeah, sounds like something strange in the “threading” stuff, then. You
shouldn’t have run out of memory, likely.
I recommend cooperating processes, using shared memory if they need to
share data, rather than any of the threading stuff. It works more
and consistently, and there is little (if anything) that threading gives
you over this model.
OK, I’ll be using traditional process stuff.
I think you’ll find it easier, too. Maybe a bit more porting work,
but far less debugging and strange limitations problems. (Another
issue you’ll be avoiding – much of the C library under QNX6 was thread
safe, while much under QNX4 was not.)
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