[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.
>
> This is also an illustration of why we moved past the very simple V1
> API. In order to add this functionality to V1 we would have had to
> extend V1 and we decided that after a while V1-extended would be
> a horrible mess. So between the choice of extending V1 and adopting
> a flexible, Pthreads API, we chose Pthreads. The existence of PSE51,
> a POSIX standard that allowed us to do Pthreads without e.g. unix
> file system, made it possible.
>
> 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. 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.
>
I wasn't being critical just asking for information but I have to echo Stuart
here, if you have some speed/determinism problems with Steve's pThreads package
then I'd like to take a look at them if you don't mind.
I personally seem to be a bit out of date here - how does PSE51 differ from
1003.1x ?
Thanks for your help
Trevor
>
> --
> ---------------------------------------------------------
> Victor Yodaiken
> Finite State Machine Labs: The RTLinux Company.
> www.fsmlabs.com www.rtlinux.com
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