[coldfire-gnu-discuss] Debugging from flash

[Corrin Meyer]

It appears that _start starts at 0x400 which is where default values
that control the flash access permissions and control are stored. I
moved _start to 0x420 and fill the space between 0x400 and 0x420 with
0x0 and things seemed to start to work.

Corrin Meyer

> -----Original Message-----
> From: Corrin Meyer [mailto:Corrin.Meyer at dornerworks.com]
> Sent: Tuesday, September 09, 2008 8:55 AM
> To: coldfire-gnu-discuss at codesourcery.com
> Subject: RE: [coldfire-gnu-discuss] Debugging from flash
> 
> I have been continuing to try to debug my problem.  While I am still
not
> sure if I am doing it correctly, I have at least been able to start
> stepping though my code as long as after connecting with the sprite I
> set PC to __cs3_reset.
> 
> The problem I have now is that I am getting an access error:
> 
> 
> Remote debugging using | m68k-elf-sprite pe: versimation
> m68k-elf-sprite: Opening P&E USBMultilink port 1 (USB1 : USB-ML-CF REF
:
> M52230DEMO (PE60))
> m68k-elf-sprite: Target reset
> 0x00000000 in __cs3_interrupt_vector_coldfire ()
> (gdb) set $pc=__cs3_reset
> (gdb) si
> 0x00000406 in __cs3_reset_m52235evb ()
> (gdb)
> 0x0000040a in __cs3_reset_m52235evb ()
> (gdb)
> 0x00000410 in __cs3_reset_m52235evb ()
> (gdb)
> 0x00000414 in __cs3_reset_m52235evb ()
> (gdb)
> 0x00000416 in __cs3_reset_m52235evb ()
> (gdb)
> 0x0000041c in __cs3_reset_m52235evb ()
> (gdb)
> 0x00005620 in _start ()
> (gdb)
> 0x00005622 in _start ()
> (gdb)
> Cannot access memory at address 0x5620
> (gdb) x/4xw 0x401d0014
> 0x401d
> 
> 
> The entire block (as far as I can tell; I haven't tested every entry)
of
> flash from 0x4000 to 0x5fff is inaccessible.
> 
> Corrin Meyer
> 
> > -----Original Message-----
> > From: Corrin Meyer [mailto:Corrin.Meyer at dornerworks.com]
> > Sent: Monday, September 08, 2008 5:25 PM
> > To: coldfire-gnu-discuss at codesourcery.com
> > Subject: RE: [coldfire-gnu-discuss] Debugging from flash
> >
> > Sorry, I forgot to include the exception frame.  That is actually
what
> I
> > was trying to look into but it doesn't seem to make sense to me.
The
> > following GDB session output was from attempting to debug the 'hello
> > world' program from flash. This program, when run without GDB, runs
> > fine.  It can be debugged fine by GDB when run from RAM.
> >
> >
> > (gdb) target remote | m68k-elf-sprite pe: m52235evb Remote debugging
> > using | m68k-elf-sprite pe: m52235evb
> > m68k-elf-sprite: Opening P&E USBMultilink port 1 (USB1 : USB-ML-CF
REF
> :
> > M52230DEMO (PE60))
> > m68k-elf-sprite: Target reset
> > 0x00000000 in __cs3_interrupt_vector_coldfire ()
> > (gdb) c
> > Continuing.
> >
> > Program received signal SIGTRAP, Trace/breakpoint trap.
> > 0x00000f5e in __cs3_isr_illegal_instruction ()
> > (gdb) p $sp
> > $1 = (void *) 0x20007f88
> > (gdb) x/4xw $sp
> > 0x20007f88:     0x20007fd4      0x40102708      0x00000002
> > 0xfffffffe
> > (gdb)
> >
> >
> > This exception frame doesn't seem to make a whole lot of sense to
me.
> >
> > I did make some progress though.  If I manually set $pc =
__cs3_reset
> > and $sp = 0x20008000 and then issue the continue command, it
executes
> as
> > expected. Also I can add breakpoints if I use 'hbreak' but it
doesn't
> > seem to add hardware breakpoints by default.
> >
> > Corrin Meyer
> >
> > > -----Original Message-----
> > > From: Corrin Meyer [mailto:Corrin.Meyer at dornerworks.com]
> > > Sent: Monday, September 08, 2008 10:42 AM
> > > To: coldfire-gnu-discuss at codesourcery.com
> > > Subject: RE: [coldfire-gnu-discuss] Debugging from flash
> > >
> > > It actually is not a M52235EVB but the ColdFire is configured like
a
> > > M52235EVB.  I have been able to successfully run and debug
> > applications
> > > from RAM.  It is just once I go to Flash that I am getting this
> > problem.
> > >
> > > Corrin Meyer
> > >
> > > > -----Original Message-----
> > > > From: Daniel Jacobowitz [mailto:dan at codesourcery.com]
> > > > Sent: Monday, September 08, 2008 9:42 AM
> > > > To: Corrin Meyer
> > > > Cc: coldfire-gnu-discuss at codesourcery.com
> > > > Subject: Re: [coldfire-gnu-discuss] Debugging from flash
> > > >
> > > > On Mon, Sep 08, 2008 at 09:21:09AM -0400, Corrin Meyer wrote:
> > > > > (gdb) target remote | m68k-elf-sprite pe: m52235evb
> > > >
> > > > Just checking, is your board actually an M52235EVB or is it
> > something
> > > > similar but slightly different?
> > > >
> > > > > Program received signal SIGTRAP, Trace/breakpoint trap.
> > > > > 0x00000e12 in __cs3_isr_illegal_instruction ()
> > > > > (gdb)
> > > >
> > > > At this point, I'd suggest you check the exception frame on the
> > stack
> > > > to see what instruction was illegal.
> > > >
> > > > > I would expect that after issuing the continue command that
the
> > > program
> > > > > should execute just as if the board had been booted.  Am I
> missing
> > > > > something?
> > > >
> > > > Almost the same.  The only difference is that the initialization
> > > > sequence in the board file is executed first; this is to support
> > > > programs run from RAM, which may require the memory controller
> > > > to be initialized first.  But in general the initialization
> sequence
> > > > does not cause a problem if executed twice.
> > > >
> > > > --
> > > > Daniel Jacobowitz
> > > > CodeSourcery