m68k gdb issue with skyeye

m68k gdb issue with skyeye

[Joel Sherrill]

Hi,

Michael Kang and I have run into something with
m68k gdb and don't know how to fix it.  The executable
is for a coldfire mc5272.

With m68k-rtems* (basically m68k-elf) on gdb 6.8,
connecting to the Skyeye gdbserver gives this.

(gdb) tar remote :12345
Remote debugging using :12345
Remote 'g' packet reply is too long: 
000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

Michael tried gdb 6.8 targeting m68k-linux and
it connects OK.

I tried gdb 6.6 m68k-rtems and it connects and
appears to work OK.

It looks like the way the maximum packet size is
calculated has changed since 6.6 and is dependent
on number of registers.

Does anyone see what the subtle difference is that
is breaking it for m68k-rtems?

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill@OARcorp.com        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
   Support Available             (256) 722-9985

Re: m68k gdb issue with skyeye

[Andreas Schwab]

Joel Sherrill <joel.sherrill@oarcorp.com> writes:

> Michael Kang and I have run into something with
> m68k gdb and don't know how to fix it.  The executable
> is for a coldfire mc5272.
>
> With m68k-rtems* (basically m68k-elf) on gdb 6.8,
> connecting to the Skyeye gdbserver gives this.
>
> (gdb) tar remote :12345
> Remote debugging using :12345
> Remote 'g' packet reply is too long:
> 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

That probably means the server and the debugger don't agree about the
size of the floating point registers.  The coldfire has only 64-bit fp
regs.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: m68k gdb issue with skyeye

[Michael Snyder]

On Mon, 2008-08-11 at 21:46 -0500, Joel Sherrill wrote:
> Hi,
> 
> Michael Kang and I have run into something with
> m68k gdb and don't know how to fix it.  The executable
> is for a coldfire mc5272.
> 
> With m68k-rtems* (basically m68k-elf) on gdb 6.8,
> connecting to the Skyeye gdbserver gives this.
> 
> (gdb) tar remote :12345
> Remote debugging using :12345
> Remote 'g' packet reply is too long: 
> 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
> 
> Michael tried gdb 6.8 targeting m68k-linux and
> it connects OK.
> 
> I tried gdb 6.6 m68k-rtems and it connects and
> appears to work OK.
> 
> It looks like the way the maximum packet size is
> calculated has changed since 6.6 and is dependent
> on number of registers.
> 
> Does anyone see what the subtle difference is that
> is breaking it for m68k-rtems?

I have run into something similar -- yes there was a change in the way
this was computed, in fact I don't think it used to ever check if the
packet was too long (only if it was too short).