[ECOS] arm-elf-gdb (target remote) -- breakpoint issue

[Michael Anburaj]

Hi Gary,

Thanks for the email. I had some email issues & did not see this email until 
now. With the -g option it works great!

I have posted another issue which is to do with the finish command. Let me 
know your thoughts on it.

Thanks a lot,
-Mike.

>From: Gary Thomas <gary@mlbassoc.com>
>To: Michael Anburaj <embeddedeng@hotmail.com>
>CC: eCos Discussion <ecos-discuss@ecos.sourceware.org>
>Subject: Re: [ECOS] arm-elf-gdb (target remote) -- breakpoint issue
>Date: Mon, 07 Feb 2005 06:35:18 -0700
>
>On Mon, 2005-02-07 at 13:24 +0000, Michael Anburaj wrote:
> > Hi,
> >
> > Tools used:
> > GNU gdb 5.3 (insight)
> > LPC2106 board running ARM remote GDB stubs (over UART)
> >
> > Short description:
> > When I try to set a breakpoint at a thumb C-function starting at address
> > 0x40000278, GDB debugger (insight) sends a (GDB protocol) command to 
>write
> > 0xbebe (Instruction which would generate a Undef exception) at 
>0x40000282 &
> > not at 0x40000278. Which is actually the functionÿs exit & not the 
>entry.
> >
> > Detailed description:
> > I issue the following commands on the GDBÿs console
> >
> > $ target /dev/com1
> > $ load
> > $ b APP_vMain
> > $ c
> >
> > And GDB log file reads as follows <Just the important lines are included
> > here>:
> >
> > c b APP_vMain
> > w $m40000278,2#60
> > r +$00b5#f7
> > w +$m4000027a,2#89
> > r +$0248#ce
> > w +$m4000027c,2#8b
> > r +$00f0#f6
> > w +$m4000027e,2#8d
> > r +$02fb#2a
> > w +$m40000280,2#59
> > r +$01bc#26
> > w +
> > c c
> > w $Z0,40000282,2#a4
> > r +$#00
> > w +$m40000282,2#5b
> > r +$0047#cb
> > w +$M40000282,2:bebe#03
> > r +$OK#9a
> > w +$Hc0#db
> >
> >
> > Clipping from the image disassembly around APP_vMain() function:
> >
> > 40000274: 4000fc00 andmi pc, r0, r0, lsl #24
> >
> > 40000278 <APP_vMain>:
> > 40000278: b500      push {lr}
> > 4000027a: 4802      ldr r0, [pc, #8] (40000284 <.text+0x184>)
> > 4000027c: fb02f000 bl 40000884 <CONSOL_SendString>
> > 40000280: bc01      pop {r0}
> > 40000282: 4700      bx r0
> > 40000284: 0ff0      lsr r0, r6, #31
> > 40000286: 4000      and r0, r0
> >
> > GDB reads the 1st 5 instructions staring 0x40000274 (APP_vMain) & 
>finally
> > sets the Break (Undef) instruction at the 6th instruction. Why?
>
>Because that's the first user instruction in the function.
>The first 5 instructions are the function preamble.
>
> >
> > Please help me understand the issue behind this.
>
>Do you have a problem, other than the location chosen for the
>breakpoint?  Does it work (or not)?
>
>--
>------------------------------------------------------------
>Gary Thomas                 |  Consulting for the
>MLB Associates              |    Embedded world
>------------------------------------------------------------
>



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