exception vectors

Hollis Blanchard hollis at penguinppc.org
Mon Oct 31 13:28:49 EST 2005

On Oct 30, 2005, at 6:35 PM, Ingmar wrote:
> I am trying to overwrite the exception vector space of an ibook G4 :).


> I have set up (for every exception) a small piece of code, that's a 
> prefix of a
> handler to be called. My problem is, that writing the “small” chunks 
> of code to
> the exception vector space gives no problem(so it seams) but writing 
> all the
> pieces of code as one chunk gives a exception [dsi, dsisr 0x42000000], 
> this
> indicates a store problem.

Code please. You're just calling memcpy?

> I have tried different modes of copying, mmu on/off, also chanced the 
> WING bit,
> switched the exception prefix on.

You could not have gotten a DSI if you disabled the MMU...

> I don't believe putting the exception vectors to there “place” one by 
> one is the
> right way, in the Linux kernel the kernel get relocated and the code 
> comes into
> place. I have taken this as an example, unfortunately to to result :(..

So you are not trying to overwrite Linux's functioning exception 
handlers, but rather trying to write your own OS?

>  - Am I overlooking something?
>  - Is the a “standard way” to overwrite the exception vector space of 
> a powerpc?

Do you think this is a common task? :)


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