Machine interface

Machine interface

[Greg Law]

Hi,

I'm trying to find some info on GDB/MI.  I've read the info pages.  They 
seem to be half finished, and specifically don't talk about one actually 
interfaces with gdb/mi.  ie. it doesn't seem to be via stdin of the gdb 
processes (typing -break-point at it causes "unknown command" errors.  
Do I need to open a socket to it or some such?  Or do I just have the MI 
syntax wrong?

TIA,

Greg

Re: Machine interface

[Bob Rossi]

On Fri, Mar 18, 2005 at 04:00:57PM +0000, Greg Law wrote:
> Hi,
> 
> I'm trying to find some info on GDB/MI.  I've read the info pages.  They 
> seem to be half finished, and specifically don't talk about one actually 
> interfaces with gdb/mi.  ie. it doesn't seem to be via stdin of the gdb 
> processes (typing -break-point at it causes "unknown command" errors.  
> Do I need to open a socket to it or some such?  Or do I just have the MI 
> syntax wrong?

If you start GDB on the command line, you can use GDB the same way you
use the CLI, of course with different syntax.

The documentation for setting breakpoints in MI mode is here,
   http://sources.redhat.com/gdb/current/onlinedocs/gdb_25.html#SEC250

in particular, try, '-break-insert main'

Bob Rossi

Re: Machine interface

[Daniel Jacobowitz]

On Fri, Mar 18, 2005 at 11:05:36AM -0500, Bob Rossi wrote:
> On Fri, Mar 18, 2005 at 04:00:57PM +0000, Greg Law wrote:
> > Hi,
> > 
> > I'm trying to find some info on GDB/MI.  I've read the info pages.  They 
> > seem to be half finished, and specifically don't talk about one actually 
> > interfaces with gdb/mi.  ie. it doesn't seem to be via stdin of the gdb 
> > processes (typing -break-point at it causes "unknown command" errors.  
> > Do I need to open a socket to it or some such?  Or do I just have the MI 
> > syntax wrong?
> 
> If you start GDB on the command line, you can use GDB the same way you
> use the CLI, of course with different syntax.
> 
> The documentation for setting breakpoints in MI mode is here,
>    http://sources.redhat.com/gdb/current/onlinedocs/gdb_25.html#SEC250
> 
> in particular, try, '-break-insert main'

More specifically, Greg, I think you're missing the "-i=mi" option.

-- 
Daniel Jacobowitz
CodeSourcery, LLC

Re: Machine interface

[Alain Magloire]

> 
> Have a look at the -var-* commands.  The testsuite is currently the best 
> source of examples.
> 

In other words try:

(gdb)
-var-create - * b
...
-var-evaluate-expression var1


Using the varobj, as shown to be more reliable.
and we use -data-evaluate-expression only for hovering or quick evaluation.

Re: Machine interface

[Andrew Cagney]

Have a look at the -var-* commands.  The testsuite is currently the best 
source of examples.

Andrew

Machine interface

[jacques]

Hello, I've been doing some MI interface testing, and am in need of some 
grammar clarifications. After running until a breakpoint, I do the 
following:

(gdb)
-data-evaluate-expression b
^done,value="{<_Vector_base<int,std::allocator<int> >> = 
{<_Vector_alloc_base<int,std::allocator<int>,true>> = {_M_start = 
0x804aa50, _M_finish = 0x804aa58, _M_end_of_storage = 0x804aa58}, <No 
data fields>}, <No data fields>}"

Which is of the format:
output => result-record => "^" result-class ( "," result )
result-class => "done"
result => variable "=" value
value => tuple
tuple => "{" result "}"
...

Now all is well and fine, however the meat of the output, being the 
variable and value nonterminal symbols are unparseable! Indeed, they are 
composed of:
variable => string
value => const => c-string (since I can't fanthom not running into a 
const value after a while)

In this case, <_Vector_base<....>> is unparseable, and I wouldn't be 
able to know how to handle all cases. Furthermore, I don't see the 
distinction between c-string and string. I see how the production would 
depend on the programming language being being debugged, but it seems 
quite important to me.
--Jacques