Re: [patch][rfa] SID --trace-semantics output

[Dave Brolley <brolley at redhat dot com>]

Frank Ch. Eigler wrote:

> brolley wrote:
>
>  
>
> > A client of ours, for whom we're developing a SID port, requested
> > that SID's semantic trace show the actual value stored, accounting
> > for read-only fields and other side effects, rather than showing the
> > value which was attempted to be stored. [...]
> >    
>
> Especially for bits outside the CPU, this has the potential to
> mislead, in that the disassembly trace would not represent the actions
> of the CPU.
but it would represent the actual result of the operation, which is what 
they want. Makes sense to me too, FWIW.

> > I eventually came up with the notion that the write/set methods of
> > SID's busses, control registers, memory access methods and hardware
> > write handers could return the actual value written. [...]
> >    
>
> I am quite unfond of this approach.  It is a messy and limited way of
> providing just one more level of tracing.  Have you considered instead
> of all this the addition of tracing flags in the various devices that
> thusly mutilate their data?  That way, when they detect an incoming
> write (from whatever source), they can print the final afterimage.
> With carefully arranged tracing code in cgen_cpu, the additional
> messages from those peripherals could appear properly intermingled.
>  
This idea sounds reasonable and more in line with the SID architecture. 
I should have asked before I leaped :-)

Thanks,
Dave