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Re: Application Exception Handling

kalyani <> writes:

> Hi, thanks for the reply. Actually i am new to this concept, i have gone
> through the links which you have sent. How to write our own exception
> handlers into VSR is what i want to know. I want to implement this at
> Application level. Kernel exception is the default configuration as i
> understood from the document. It is given that VSRshould be written in
> assembly language for Application exception handler. Can you please clarify
> all my doubts and please can you provide me any example codes for this
> exception handlers if any which have already been  implemented.

VSRs are entered after minimal processing and with the state as close
to the CPU exception entry state as possible. If there has been any
decoding of the exception source then some registers may have been
saved somewhere architecture specific and will now contain some other
data -- usually some representation of the exception number or VSR
table index.

Plugging the VSRs is not done very often, and there are no
examples. You don't say what architecture you are working on, so any
example may not be appropriate. Mainly you need to know about how the
CPU delivers exceptions.

The best thing to do is to look at how the default exception VSR
handler works in vectors.S and duplicate it as far as is necessary for
your purposes.

Nick Garnett                                 eCos Kernel Architect            The eCos and RedBoot experts

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