Re: Is there single step debugging support being added to aarch64-linux?

[pinskia at gmail dot com]

> On Jun 15, 2015, at 4:07 AM, Prafull Suryawanshi <prafull.net@gmail.com> wrote:
> 
> I am using gdb to talk to kgdb, so is not issue with gdb?
> gdb is not able to set software single step like it do for arm.
> There is implementation for gdbarch_software_single_step_p in arm gdb
> but not in aarch64 gdb.
> 
> In fact, I had small implementation to get next_pc at fixed offset
> (+4) and it starts working. (implementing full version)


Why can't you use the hardware single stepper for kgdb?

Thanks,
Andrew

> 
> Let me know.
> 
> Thanks,
> Prafull
> 
> 
> On Mon, Jun 15, 2015 at 4:27 PM, Prafull Suryawanshi
> <prafull.net@gmail.com> wrote:
>> I am using kgdb and trying to do single step (software single step).
>> I see that infrun loops. (I enabled remote_debug option and compiled
>> gdb 7.7 as 7.9 has issue with connection)
>> 
>> infrun: clear_proceed_status_thread (Thread 3462)
>> infrun: clear_proceed_status_thread (Thread 3444)
>> infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT, step=1)
>> infrun: resume (step=1, signal=GDB_SIGNAL_0), trap_expected=1, current
>> thread [Thread 3462] at 0xffffffc00021014c
>> Sending packet: $Hcd86#7d...Ack
>> Packet received: OK
>> Sending packet: $s#73...Ack
>> infrun: wait_for_inferior ()
>> Packet received: T05thread:0d86;
>> infrun: target_wait (-1, status) =
>> infrun:   42000 [Thread 3462],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: infwait_normal_state
>> infrun: TARGET_WAITKIND_STOPPED
>> Sending packet: $g#67...Ack
>> Packet received:
>> 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
>> infrun: stop_pc = 0xffffffc000210150
>> Sending packet: $mffffffc000210150,4#4d...Ack
>> Packet received: fd030091
>> Sending packet: $mffffffc00021014c,4#7f...Ack
>> Packet received: fd7ba3a9
>> Sending packet: $mffffffc000210150,4#4d...Ack
>> Packet received: fd030091
>> infrun: stepping inside range [0xffffffc00021014c-0xffffffc000210170]
>> Sending packet: $Z0,ffffffc00021014c,4#c8...Ack
>> Packet received: OK
>> infrun: resume (step=1, signal=GDB_SIGNAL_0), trap_expected=0, current
>> thread [Thread 3462] at 0xffffffc000210150
>> Sending packet: $Hc0#db...Ack
>> Packet received: OK
>> Sending packet: $s#73...Ack
>> infrun: prepare_to_wait
>> 
>> Then I build the gdb using arch_dump enable option
>> gdbarch_dump: gdbarch_software_single_step_p() = 0
>> 
>> I see that in gdb code, function aarch64_linux_software_single_step not present.
>> 
>> I guess above loop expected if aarch64_linux_software_single_step absent, right?
>> 
>> Thanks,
>> Prafull
>> 
>>> On Mon, Jun 15, 2015 at 4:08 PM, Andreas Schwab <schwab@suse.de> wrote:
>>> Prafull Suryawanshi <prafull.net@gmail.com> writes:
>>> 
>>>> I am trying it on 64 bit armv8 system but not able to doit.
>>>> Found issue in gdb source code and absence of this function in
>>>> aarch64-linux-tdep.c file. Anyone knows if support getting added or
>>>> not?
>>> 
>>> The stepi command is working fine on aarch64.  What do you get if you
>>> try it?
>>> 
>>> Andreas.
>>> 
>>> --
>>> Andreas Schwab, SUSE Labs, schwab@suse.de
>>> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
>>> "And now for something completely different."