Re: [Gems-users] modules

[Dan Gibson <degibson@xxxxxxxx>]

Dave Z. wrote:
> Hello,
>
> I'm working on a new instruction decoder module in
> Simics. The new instructions will basically send
> special CacheMsg to the cache controller.
As Mike has said before, the CacheMsg types are defined in 
$GEMS/protocols/RubySlicc_Exports.sm. Modify that file to add a new 
CacheMsg type.
>  I'm
> wondering if it is possible to establish such
> interaction with the cache controller from another
> Simics module. 
>   
Yes.
> For example, one of the instructions will take
> destination cpu number (stored in a register)
You can use SIM_read_register() from the Simics interface to access this 
register.
>  as an
> argument and send some message to the cache
> controller. The cache controller will then use the
> destination cpu number and take some actions. Since
> Ruby is implemented as a module, I'm wondering if it
> is possible to access Ruby from another Simics module.
>   
Yes, that is possible.
> Does this approach introduce any inefficiency to the
> system?
>   
Yes, module-to-module communication is bulky, complicated, and slow. See 
the Ruby/Opal interface, defined in several files, most of which have 
already been discussed on this list (see the web archives). 
OpalInterface.[Ch], hfa.[Ch], opal.c, ruby.c, the two init.[Ch]s are the 
important files.
> Finally, I believe I need to compile the decoder
> module together with Ruby as it will use Ruby's
> sequencer methods. 
You need to decide if you want to couple your functionality INTO Ruby or 
have it in a separate Simics module. Either approach will work. Making 
it part of Ruby will be substantially easier.
> Where should I put the decoder
> module in the Ruby tree? Thank you for your help.
>   
Wherever you like. Organize your code in whichever way seems best to you.
> Regards,
>
> Dave
>
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