Re: Real-time alarms

Rodney W. Grimes (freebsdgndrsh.dnsmgr.net)
Mon, 20 Sep 1999 11:05:40 -0700 (PDT)

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> > > Ouch.
> > >
> > > do you REALLY suggest things along the lines
> > >
> > > set proc/priv=(... , .... , .... )
> >
> > Yes, at least the functionality, we don't have to use the VMS DCL
> > interface to it. set proc/priv= just flips bits in the process
> > header area.
>
> IIRC, it 'flips bits' in a dedicated VAXCPU register.

You surely don't really know how it works if you think that. It sets
bits in the process header area, or PCB. It does not directly set
bits in any dedicated CPU register. Some process priviledges do effect
what bits in the CPU you can fool with, like CMKRN allows your user
land code to execute as if it was running in kernel mode. Basically
your user code tries to do a Change Mode to Kernel instruction, VMS
traps that, looks at your PCB, goes, ohh, okay he is allowed to do that,
sets the bits in the register for you faking the instruction and returning
to your code.

>
> > You have a better idea??
>
> NO, so I will voluntarily shut up .

:-). No need to do that, just find me a better idea!! I am open
to anything, need more input.. need more input... need more COFFEE!!!

-- 
Rod Grimes - KD7CAX - (RWG25)                    rgrimesgndrsh.dnsmgr.net
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• Next message: Kip Macy: "Re: Out of mbuf clusters"
• Previous message: Dag-Erling Smorgrav: "Re: Out of mbuf clusters"
• In reply to: Joao Carlos: "Re: Out of mbuf clusters"
• Next in thread: Robert Watson: "Access Control (was: Re: Real-time alarms)"

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