[EMAIL PROTECTED] writes:
> On Thu, Jun 29, 2000 at 12:44:52PM -0600, Erik Andersen wrote:
> > b) RTAI now has a feature called LXRT hard real-time (in it's early days)
> > that allows the use of hard real-time from user-space programs (thus has
> > the potential to use the process MMU protection). Note when a thread is in
> > hard real-time mode, it still may not access Linux systems calls.
>
> I think this is a very clever idea and would be semi-happy to add it
> to the RTLinux distribution if it were done in a way that was safe
> and portable. So far, the explanations I've seen, however, are kind
> of scary. I really don't like the use of "int xx" to provide a
> second copy of the system calls, the stated need to run hard RT
> locks around the Linux scheduler, and some other features (including
> some fuzziness about what happens when a user forgets to mlockall or
> uses a shared library).
I'd still prefer the scheme I suggested a while back: run Linux
processes on the RT scheduler if they have RT priority, and switch
between RT and Linux scheduler whenever going between user-space and
kernel-space.
This would mean you get complete access to all system calls and user
libraries within a RT process, without having to bloat the kernel with
a pile of pseudo-RT hacks.
It would also mean we could consider ripping out SCHED_FIFO and
SCHED_RR from the Linux scheduler, hence simplifying it.
Somebody please find the time to implement this :-)
Regards,
Richard....
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