> Zdenek Kabelac wrote:
> > there are no kernel modification - CLI/STI are the enemies and I would
> > like to know how they are handled in RTAI. What happens when
> > SBLive driver calls spinlock_irq_safe ??
>
> One of the main advantages of RTAI (but my understanding is that RTL
> has included this now ... see what I mean) is that it doesn't take RT
> control over from Linux right away. RTAI inserts generalized hooks
> into Linux which are not used right away. These hooks end up calling
> on the normal Linux functions as long as RTAI isn't installed. Once
> installed, RTAI uses those hooks to take the control of the system.
> Therefore, if SBLive calls on spinlock_irq_safe, it is caught by RTAI.
> Meanwhile RTAI uses true locking facilities to further it's ends.
I don't understand this - you mean when CPU executes CLI/STI its being catch
by some trap ???? - I could imagine that Linux kernel runs on
different level of protection (i386 has four of them if I remember this
correctly), but this exception handling takes quite a lot of CPU cycles.
Is there any explanation/article I could learn more about this "magic" ??
(Basicaly how RTAI could hold with timelimit if the linux-driver calls CLI
and wait in busy-loop for 1ms)
(I still suppose there are no internal kernel modifications and I could
use RT just with module insert of RTAI modules)
--
There are three types of people in the world:
those who can count, and those who can't.
Zdenek Kabelac http://i.am/kabi/ [EMAIL PROTECTED] {debian.org; fi.muni.cz}
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