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Re: MORE question about "VIRTUAL_VECTOR_SUPPORT"


Tony Ko wrote:
> 
> Tony Ko wrote:
> >>
> >> hi.
> >> look at the satement below,
> >> "Enable use of virtual vector calling interface. Virtual vector
> support
> >> allows
> >> the HAL to let the ROM monitor handle certain operations."
> >>
> >> does this satement mean " when exception occurs  while ecos running,
> >> the exception can be processed by REDBOOT" ?
> >> I think ROM monitor is same with REDBOOT in this case.
> >> If so, some exception can be processed by REDBOOT exception handler
> even
> >> while eCos running, right?
> 
> >I'm not quite clear on what you are asking here. But yes the
> application
> >will hand over certain operations to RedBoot using virtual vectors.
> 
> ==> Does this mean that " a RAM-loaded eCos app can hand over exception
> processing to
>        ROM-loaded REDBOOT using virtual vectors ? "
>        Then why does app do that?

Define "exception" and I might have a clue what you're asking.

> >But in most cases when it comes to processor exceptions, a RAM-loaded
> eCos
> >app will not take over the processor exception vectors in the first
> place -
> >but that's not related to *virtual* vectors.
> 
> ==> I don't understand this statement clearly. Could you explain in
> more detail?
>        And what does VIRTUAL really mean in this case?

Not real vectors - they are vectors (in the computer science sense) but
they are not *hardware* vectors, so we named them "virtual".

Jifl
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