Re: Reverse debugging for arm baremetal targets?

[Hui Zhu <teawater@gmail.com>]

On Mon, Jul 22, 2013 at 2:10 PM, Terry Guo <flameroc@gmail.com> wrote:
> On Mon, Jul 22, 2013 at 10:07 AM, Hui Zhu <teawater@gmail.com> wrote:
>> On Mon, Jul 22, 2013 at 9:37 AM, Terry Guo <flameroc@gmail.com> wrote:
>>> Hi there,
>>>
>>> Is this feature enabled for arm baremetal targets? If not, is it
>>> possible to do so and what kind of problems we need to solve to
>>> achieve this? Thanks in advance for your help.
>>>
>>> Best Regards,
>>> Terry
>>
>> If just for reverse debug, I think it is not depend on the arch.  So I
>> think it is OK for ARM.
>>
>> And if I remember is right, simics support it.
>>
>> Thanks,
>> Hui
>
> Thanks for your reply. I did some tests and it seems to me that
> reverse debugging doesn't work for baremetal targets. My test includes
> a ARM Cortex-M3 board running a baremetal program, a gdb server and a
> baremetal gdb. The gdb version is:
>
> GNU gdb (GDB) 7.6
>
> After I connect to M3 board and run command "record", I got:

This error is about process record but not reverse debug.

>
> Breakpoint 1, main () at main.cpp:24
> 24 xyz = 0;
> (gdb) record
> Process record: the current architecture doesn't support record function.

This is the reason why you cannot use reverse debug commands.

You got this error is because:
  /* Reversible debugging, process record.  */
  set_gdbarch_process_record (gdbarch, arm_process_record);
This line is called in arm_linux_init_abi but you are not a linux target.

I found all the "set_gdbarch_process_record" is called in
xxx_linux_init function make it depend on Linux.
I forget why I do it.  :P
I think 2 reasons let me do it:
1. syscall record just support linux.
2. make it can pass review.  :P

But most of prec function is just to record the behavior of
instruction.  So maybe we can move it to arch init code.

Thanks,
Hui

> (gdb) show ar
> architecture  args          arm
> (gdb) show architecture
> The target architecture is set automatically (currently arm)
> (gdb) n
> 26 foo ();
> (gdb) s
> foo () at main.cpp:16
> 16  xyz = 1;
> (gdb) n
> 17  return bar ();
> (gdb) s
> bar () at main.cpp:10
> 10  xyz = 2;
> (gdb) reverse-next
> Target remote does not support this command.
>
> Am I doing something wrong? Please advise.




>
> BR,
> Terry