Based on the feedback, updated the patch with the review comments.
    
[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