Re: Reading a static variable in Python

[Chris Johns <chris at contemporary dot net dot au>]

On 11/03/2010 4:05 AM, Tom Tromey wrote:
> > > > > > "Chris" == Chris Johns<chris@contemporary.net.au>  writes:
>
> Chris>  I am adding pretty printers for RTEMS to gdb. In the RTEMS operating
> Chris>  system elements such as a semaphore are given an id. I would like to
> Chris>  print the actual semaphore data given a semaphore id. To do this I
> Chris>  need to read a kernel structure from a table indexed via a bit field
> Chris>  in the id. As an example the semaphore's table is declared in RTEMS
> Chris>  as:
>
> Chris>  RTEMS_SEM_EXTERN Objects_Information  _Semaphore_Information;
>
> This isn't really enough information for us to help you.
> What does Objects_Information look like?

Yes sorry about that. It is a C struct [1].

> Chris>  I am stuck on how to create a new gdb.Value variable in Python.
>
> Use gdb.parse_and_eval.

Nice. This is an excellent solution. I suppose being an expression it 
can do the pointer maths as well. I was looking at ways to construct a 
gdb.Value with a gdb.Symbol as an argument.

>  This wasn't added until after 7.0.

I am using a 7.1 snapshot as it has the 'source' command to load a 
Python file. This is also an excellent addition.

Chris

[1] 
http://www.rtems.org/onlinedocs/doxygen/cpukit/html/structObjects__Information.html