[EMAIL PROTECTED] wrote:
>
> On Wed, Aug 30, 2000 at 03:18:23PM +0100, Trevor Woolven wrote:
> > BTW, can anyone *really* explain the point of non-portable extensions in a
> > (supposedly) portable standard? I'm not saying they're wrong but they don't
> > make sense (to me).
>
> We follow POSIX PSE51 for reasons of simplicity, coherence, programmer
> familiarity, and because there is a real standard, not a creature of
> any company. POSIX is specified so that implementation extensions can
> be accomodated. For example, to reserve a RTLinux only processor in
> an SMP system, we have
> pthread_kill(pthread_linuxthread(),RTL_SIG_SUSPEND_LINUX );
> Of course, there is no signal RTL_SIG_SUSPEND_LINUX in the
> POSIX specifications and this code will fail on Chorus -- but our
> goal is to make RTLinux programming easy, not to make RTLinux as slow
> and clumsy as Chorus. And the POSIX standard is designed to allow for
> such extensions.
I understand the reason for these non-portable extensions, but they
unique features to RTLinux that lock-in users under the mask of
perceived portability.
> As I have pointed out before, the purpose of Steve Papacharalambous'
> POSIX package is very much different from the purpose of our PSE51
> API -- even though we draw from the same base spec. Steve's package
> is great for people who want to port code from Chorus or Lynx or
> something to RTLinux.
Indeed, very good for people porting real applications to RTAI. I guess
from the late addition of pthread_mutex_xxx and pthread_cond_xxx to
RTLinux that you agree with his philosophy of using the Linuxthreads
package as a template.
> But RTLinux is based on fundamentally
> different design than those systems and we are trying to make a
> convenient API for that design. So it misses the point to critique
> Steve's package for lack of speed/determinism or our work for
> exposing the RTLinux design.
If you has some information that shows Steve's package is not
deterministic, I'd love to see it.
Regards, Stuart
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