Re: beginner

[srinivas bakki <srinivasbakki@yahoo.co.uk>]

Thank you all people, it seems i have enough at hand
now. may be i'll keep pestering with all those silly
doubts though :)

Regards
Srinivas Bakki

--- Arun Paneri <p26a@yahoo.com> wrote:

> See this mail chain if it helps you  (Courtesy
> Michael Snyder)
> 
> Also go through this site
>
http://sourceware.org/gdb/current/onlinedocs/gdbint_toc.html
> 
> Regards.
> 
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> YAHOO.Shortcuts.document_title = "Re: Pls help:
> regarding gdb internals";
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> 
> On 
> Wed, 
> 2008-01-16 
> at 
> 11:59 
> -0800, 
> Arun 
> Paneri 
> wrote:
> > 
> Hi 
> All,
> > 
> >  
> I 
> am 
> new 
> to 
> gdb 
> code 
> and 
> trying 
> to 
> learn 
> more 
> things. 
> i 
> need 
> help 
> regarding 
> gdb 
> internals.
> > 
> > 
> Can 
> anyone 
> write 
> few 
> lines 
> about 
> how 
> does 
> gdb 
> internally 
> works.
> >  
> I 
> went 
> to 
> "Gdb 
> internals 
> guide" 
> but 
> couldn't 
> find 
> much 
> information 
> > 
> specifically 
> which 
> i 
> am 
> looking 
> for. 
> I 
> want 
> information 
> like 
> > 
> when 
> we 
> give 
> command
> > 
> "$gdb 
> test.exe" 
> > 
> then 
> how 
> internaly 
> it 
> works. 
> Does 
> it 
> start 
> reading 
> symbols
> >  
> and 
> start 
> making 
> symbol 
> table 
> with 
> this 
> command 
> ? 
> 
> Yes.
> 
> > 
> Does 
> it 
> start 
> creating 
> stack 
> frames 
> as 
> we 
> give 
> command 
> "run" 
> or 
> before 
> even 
> that 
> with 
> "$gdb 
> test.exe"?
> 
> No, 
> and 
> no.  
> Before 
> you 
> "run" 
> a 
> program, 
> there 
> are 
> no 
> stack 
> frames.
> But 
> gdb 
> does 
> not 
> start 
> constructing 
> its 
> internal 
> stack 
> frame
> representation 
> until 
> the 
> program 
> STOPS, 
> eg. 
> at 
> a 
> breakpoint 
> or
> after 
> executing 
> a 
> "step".
> 
> >  
> I 
> am 
> basically 
> interested 
> to 
> know 
> about 
> creation 
> of 
> frames 
> and 
> how 
> does 
> gdb 
> read 
> them 
> back 
> when 
> we 
> give 
> "backtrace" 
> command? 
> 
> For 
> performance 
> reasons, 
> gdb 
> tries 
> to 
> construct 
> its 
> stack 
> frame
> data 
> lazily 
> -- 
> it 
> postpones 
> the 
> work 
> whenever 
> possible.
> 
> So, 
> in 
> general, 
> whenever 
> the 
> program 
> stops, 
> gdb 
> will 
> construct
> one 
> (and 
> hopefully 
> only 
> one) 
> stack 
> frame 
> -- 
> the 
> one 
> for 
> the 
> function 
> in 
> which 
> the 
> program 
> stopped.
> 
> If 
> you 
> give 
> the 
> "up" 
> command, 
> gdb 
> will 
> construct 
> the 
> next
> (one) 
> stack 
> frame.
> 
> If 
> you 
> ask 
> for 
> "backtrace 
> 10" 
> it 
> will 
> construct 
> the 
> next
> ten 
> stack 
> frames.  
> And 
> if 
> you 
> ask 
> for 
> a 
> full 
> backtrace, 
> gdb 
> will 
> construct 
> as 
> many 
> stack 
> frames 
> as 
> it 
> can 
> find.
> 
> > 
> > 
> I 
> am 
> not 
> sure 
> but 
> i 
> think 
> to 
> creat 
> a 
> frame 
> it 
> calls 
> _initialize_stack 
> (void)
> 
> No.  
> That 
> function 
> is 
> the 
> initializer 
> for 
> the 
> "stack.c" 
> module.
> It 
> is 
> called 
> when 
> gdb 
> starts 
> up, 
> and 
> just 
> initializes 
> the 
> infrastructure 
> for 
> stack 
> manipulation.
> 
> >  
> and 
> from 
> this 
> it 
> calls 
> fun_command(char 
> *arg, 
> int 
> from_tty) 
> then 
> parse_frame_specification(char 
> *frame_exp) 
> & 
> then 
> create_new_frame(CORE_ADDR 
> addr, 
> CORE_ADDR 
> pc) 
> function.
> 
> Start 
> with 
> the 
> function 
> "get_prev_frame", 
> and 
> work 
> your 
> way 
> up 
> (and
> down) 
> from 
> there.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ----- Original Message ----
> > srinivas
> > 
> bakki
> > 
> wrote:
> > >
> > 
> Hi
> > 
> people,
> > > 
> > 
> I
> > 
> wanted
> > 
> to
> > 
> start
> > 
> going
> > 
> through
> > 
> the
> > 
> GDB
> > >
> > 
> source
> > 
> code
> > 
> to
> > 
> learn
> > 
> how
> > 
> it
> > 
> is
> > 
> implemented,
> > 
> what
> > 
> goes
> > >
> > 
> into
> > 
> the
> > 
> application
> > 
> and
> > 
> its
> > 
> various
> > 
> nuances,
> > 
> perhaps
> > >
> > 
> in
> > 
> a
> > 
> direction
> > 
> to
> > 
> be
> > 
> an
> > 
> active
> > 
> contributor
> > 
> to
> > 
> gdb.
> > > 
> > >
> > 
> But
> > 
> am
> > 
> not
> > 
> able
> > 
> to
> > 
> get
> > 
> a
> > 
> clue
> > 
> for
> > 
> the
> > 
> starting
> > 
> point.
> > >
> > 
> where
> > 
> should
> > 
> i
> > 
> start
> > 
> digging
> > 
> the
> > 
> code
> > 
> ?
> > > 
> > >
> > 
> Would
> > 
> be
> > 
> great
> > 
> if
> > 
> you
> > 
> people
> > 
> help
> > 
> me
> > 
> through
> > 
> this.
> > 
> > man
> > 
> ptrace
> > 
> > You
> > 
> should
> > 
> have
> > 
> a
> > 
> good
> > 
> understanding
> > 
> of
> > 
> how
> > 
> the
> > 
> unix
> > process
> > 
> works
> > 
> first.
> > 
> 
> 
> 
> 
>      
>
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