Re: [ECOS] Using a Mix of Posix and native calls.

[Nick Garnett <nickg at ecoscentric dot com>]

"Venkateswara Rao L." <lvenkat@lvl7.com> writes:

> Hi,
> 
> I've just started working on ecos.  I've a basic query.
> 
>  
> 
> Suppose, we use ecos native call(cyg_thread_create) to create a
> task(TASK A).  We have another timer task that implements the software
> timers. 
> 
> We have a func. timerAdd(), that sets the timeout call. It uses
> pthread_cleanup_push with actual "internal timer add function" as
> argument, followed by pthread_cleanup_pop(1) to execute the registered
> handler. The function timerAdd()  is called in the context of TASK A.
> We are getting exception while executing pthread push and pop
> instructions.  It looks to me that this exception might be happening
> because the task which makes a call to the above mentioned posix calls,
> was not created using posix pthread routines.   
> 
>  
> 
> Is my understanding correct? Can we have a mix of posix and native calls
> under some conditions?

In general, you can call non-POSIX functions from POSIX threads, but
you cannot call POSIX functions from non-POSIX threads. This is
because POSIX threads have extra state associated with them such as
signal masks, per-thread data, and the root of the cleanup stack. This
latter item is what was missing when you attempted to use
pthread_cleanup_* from an non-POSIX thread. So you need to make that
thread a POSIX thread.


-- 
Nick Garnett                                     eCos Kernel Architect
eCosCentric Limited     http://www.eCosCentric.com/   The eCos experts
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