[dsdp-dd-dev] FW: RE: -var-update using formatted value

["Marc Khouzam" <marc.khouzam@xxxxxxxxxxxx>]

Hi,

I think point 1 in the below email is good one.

I had started blurring the concept of backend and GDB, but in our DSF setup,
it is true that GDB will be running on the front-end, right?
With the GDB-Server on the backend. Therefore, whatever is cached by GDB, needs not 
be cached by our GDB/MI implementation. Is that correct?

So now, I wonder about the usefulness of two of our caches of the ExpressionService.

1- the special meta command cache may not be necessary, since GDB should already be 
caching those values.  Although this cache does work and can be a good example for
other debuggers that don't cache as GDB does.

2- the format-value cache which could simply rely on the internal GDB cache
as mentioned in the email below.  Since this cache needs a workaround to properly
work with the current implementation of var-update, it would be easier to get rid
of it.  But that means that after every 'Resume', each value, even if not changed
will need to be fetched from GDB (but not from GDB-server).

Any opinions?

Thanks

Marc
 

-----Original Message-----
From: gdb-owner@xxxxxxxxxxxxxx [mailto:gdb-owner@xxxxxxxxxxxxxx]On
Behalf Of Vladimir Prus
Sent: Thursday, January 17, 2008 1:02 PM
To: gdb@xxxxxxxxxxxxxxxxxx
Subject: RE: -var-update using formatted value

[...]

> > > If I have a varObject displaying 0x1 in hex and then I want to show the
> > > value in binary, I will need to go to the target.
> > 
> > No. GDB keeps the raw value inside the variable object, and changing
> > format only changed the way gdb converts that raw value into string.
>
> For embedded systems, we want to
> reduce the communication with GDB to a minimum, because GDB itself is
> running on a potentially slow processor, with a small bandwidth connection
> to the front-end. That is why I am trying to cache all values.

I have two observations:

1. Generally, it's best to run gdb on the same system where you run IDE,
and have it talk to remote stub on the target system. 

2. Even if you run gdb on target, changing varobj format is very fast,
so I'm not sure caching formats is an important thing to do. Did you
actually run into a case where the performance of changing format is
unacceptable?

- Volodya