Crash a RISC machine from user-mode code:

[Kevin D. Quitt]

In article <1990Aug13.053147.11714 at laguna.ccsf.caltech.edu> bruce at seismo.gps.caltech.edu (Bruce Worden) writes:
>In article <477 at demott.COM> kdq at demott.COM (Kevin D. Quitt) writes:
...
>>  If there is *any* set of
>>instructions that, from the user level, can crash a privelege-based
>>system, then that system is *broken*. 
>>    Again, just because it's broken doesn't mean it can't be useful for
>>limited applications - like single user operation.  But when you try to
>>stress the system, it's going to fail.
>
>...  These systems provide excellent 
>service for dozens of users; they have most certainly not "failed".  Not 
>bad for a "*broken*" system useful only for single user operation.
>

    Please read what I said.  I did *not* claim they were only useful for
single user mode, just that it was one condition where it could be used.
Another situation is where you have users of (well debugged) applications,
which appears to be your situation.


>Wake up.  Risc may not be perfect (is anything?), but it is providing 
>price/performance that has never before been available.


    Where did this come from? I'm not talking about RISC - I'm talking
about ANY type of computer system, RISC, CISC, DTL doesn't matter.  If
it is a multi-level privelege system, and the hardware can fail to
provide the necessary protection to the operating system, then the hardware
is broken. Period.  

-- 
 _
Kevin D. Quitt         demott!kdq   kdq at demott.com
DeMott Electronics Co. 14707 Keswick St.   Van Nuys, CA 91405-1266
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