Sun, 26 Jul 1998 00:24:48 EDT
[log in to unmask] (Samuel Mize) quoted and then wrote:
>> We want to build a safety related system (a control computer for=20
>> a flight simulator connected to a motion platform).
>> Our safty concept simply requires, that the Ada main detects a failure
>> in the C part and then shuts down the simulator.
>A rogue pointer in the C section can be used to write over anything in
>its address space: C data, Ada data, C or Ada code... If your
>hardware and OS don't detect address-space violations, the C can write
>into random parts of the Ada even if they're in separate processes, or
>even into the OS data or code.
Leaving the Ada issues and the many valid C concerns aside, I would feel
very anxious about entering a flight simulator which I know depended upon
some hardware and OS which did _not_ detect address-space violations. A
safety-related system should not skimp on the language-independent aspects
of the project. If each computer is to be connected to a big physical
machine, computer hardware cost or OS license fees can hardly be an issue.