Re: [Patch, microblaze]: Fix for remote G Packet message too long error for baremetal.

[Michael Eager <eager@eagercon.com>]

On 06/30/14 03:32, Ajit Kumar Agarwal wrote:
> Based on the feedback, updated the patch with the review comments.

How has this been tested?  Please be specific.

>
> [Patch, microblaze]: Fix for remote G Packet message too long error for baremetal.
>
>      Prior to version MicroBlaze v8.10.a,EDK 13.1, XMD's gdbserver stub returned 57
>      registers in response to GDB's G request. Starting with version MicroBlaze
>      v8.10.a, EDK 13.1, XMD added the slr and shr register, for a count of 59
>      registers. This patch adds these registers to the expected G response. This patch
>      fixes the above problem for baremetal and also supports the backward compatibility.
>
>      ChangeLog:
>      2014-06-26  Ajit Agarwal  <ajitkum@xilinx.com>
>
>          * microblaze-tdep.c (microblaze_register_names): Add
>          the rshr and rslr register names.
>          (microblaze_gdbarch_init): Use of tdesc_has_registers.
>          Use of tdesc_find_feature. Use of tdesc_data_alloc.
>          Use of tdesc_numbered_register. Use of
>          microblaze_register_g_packet_guesses. Use of
>          tdesc_use_registers. Use of set_gdbarch_register_type.
>          (microblaze_register_g_packet_guesses): New.
>          * microblaze-tdep.h (microblaze_reg_num): Add
>          field MICROBLAZE_SLR_REGNUM MICROBLAZE_SHR_REGNUM
>          MICROBLAZE_NUM_REGS and MICROBLAZE_NUM_CORE_REGS.
>          (microblaze_frame_cache): Use of MICROBLAZE_NUM_REGS.
>          * features/microblaze-core.xml: New file.
>          * features/microblaze-stack-protect.xml: New file.
>          * features/microblaze-with-stack-protect.c: New file.
>          * features/microblaze-with-stack-protect.xml: New file.
>          * features/microblaze.xml: New file.
>          * features/microblaze.c: New file.
>          * features/Makefile (microblaze-with-stack-protect): Add
>          microblaze-with-stack-protect microblaze and
>          microblaze-expedite.
>          * regformats/microblaze-with-stack-protect.dat: New file.
>          * regformats/microblaze.dat: New file.
>          * doc/gdb.texinfo (MicroBlaze Features): New.
>
>      Signed-off-by:Ajit Agarwal ajitkum@xilinx.com
>
>> In this case is it correct to say
>> If (tdesc  == NULL)
>>    tdesc = tdesc_microblaze;
>>
>> instead of tdesc_microblaze_with_stack_protect?
>
>>> Yes.
>
> Instead of tdesc_microblaze_with_stack_protect if I use tdesc_microblaze  the "G Packet message is too long" error is not resolved.
> The patch is unchanged with tdesc_microblaze_stack_protect.
>
> Thanks & Regards
> Ajit
> -----Original Message-----
> From: Pedro Alves [mailto:palves@redhat.com]
> Sent: Tuesday, June 24, 2014 6:17 PM
> To: Ajit Kumar Agarwal
> Cc: gdb-patches@sourceware.org; Michael Eager; Vinod Kathail; Vidhumouli Hunsigida; Nagaraju Mekala
> Subject: Re: [Patch, microblaze]: Fix for remote G Packet message too long error for baremetal.
>
> On 06/24/2014 01:31 PM, Ajit Kumar Agarwal wrote:
>
>>>
>>> The default is choosen to assume stack protect to make compatible with the handling of stack protect registers in XMD Debugger.
>>
>>>> But you've already added the G packet size guess for that.
>>
>> In this case is it correct to say
>> If (tdesc  == NULL)
>>    tdesc = tdesc_microblaze;
>>
>> instead of tdesc_microblaze_with_stack_protect?
>
> Yes.
>
>>
>>>> -
>>>> +  if (tdesc_data != NULL)
>>>> +    {
>>>> +      tdesc_use_registers (gdbarch, tdesc, tdesc_data);
>>>> +      set_gdbarch_register_type (gdbarch,
>>>> + microblaze_register_type);
>>>
>>>>> Hmm, why is this set_gdbarch_register_type call necessary?
>>>
>>> /* Override tdesc_register_type to adjust the types of VFP
>>>           registers for NEON.  */
>>> This is done for arm target  to set the different type for VFP
>>> registers for Neon with Boolean flags is set before this call for VFP
>>> registers. In the microblaze target it's not required for special
>>> case of stack protect as
>> the microblaze_register_type always return builtin_int for these stack protect registers.
>>
>> Right.
>
> Actually, not right...  This comment doesn't really appear to be correct:
>
>> In the microblaze target it's not required for special case of stack
>> protect as the microblaze_register_type always return builtin_int for these stack protect registers.
>
>
> static struct type *
> microblaze_register_type (struct gdbarch *gdbarch, int regnum) {
>    if (regnum == MICROBLAZE_SP_REGNUM)
>      return builtin_type (gdbarch)->builtin_data_ptr;
>
>    if (regnum == MICROBLAZE_PC_REGNUM)
>      return builtin_type (gdbarch)->builtin_func_ptr;
>
>    return builtin_type (gdbarch)->builtin_int; }
>
> MICROBLAZE_SP_REGNUM and MICROBLAZE_PC_REGNUM clearly aren't builtin_int...
>
> Doesn't your patch change the output of "ptype $sp" and "ptype $pc" ?
>
> That points at something missing in the target description:
>
>> +<!DOCTYPE feature SYSTEM "gdb-target.dtd"> <feature
>> +name="org.gnu.gdb.microblaze.core">
>> +  <reg name="r1" bitsize="32"/>
> ...
>> +  <reg name="rpc" bitsize="32"/>
>
> AFAICS, SP is "r1", and PC is "rpc".  These should be marked with type="data_ptr" and type="code_ptr" .
>
>>
>>>>> As I mentioned before, please don't forget to document the new target features in the manual.
>>>
>>> Would you mind in explaining which manual need to be changed for the new target.
>>
>>>> The GDB manual, gdb/doc/gdb.texinfo, describes all the standard XML target features.  See the "Standard Target Features" node, and add a new subsection for MicroBlaze.
>>
>> Thanks !! I will add subsection for Microblaze target.
>
> Thank you.
>
> --
> Pedro Alves
>


-- 
Michael Eager	 eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077