Re: [PATCH v1] [powerpc] Remove 512 bytes region limit if using 2nd DAWR.

[Rogerio Alves via Gdb-patches <gdb-patches@sourceware.org>]

On 11/9/20 7:24 AM, Ulrich Weigand wrote:
> On Sun, Nov 08, 2020 at 11:12:04PM -0300, Rogerio Alves wrote:
>> Power 10 introduces the 2nd DAWR (second watchpoint) and also removed
>> a restriction that limit the watch region to 512 bytes.
>>
>> 2020-11-08  Rogerio A. Cardoso  <rcardoso@linux.ibm.com>
>>
>> gdb/
>>
>> * ppc-linux-nat.c: (PPC_DEBUG_FEATURE_DATA_BP_ARCH_31): New define.
>> (region_ok_for_hw_watchpoint): Check if 2nd DAWR is avaliable before set
>> region.
> 
> This doesn't look correct, the patch not only removes the alignment
> requirement but actually removes support for 512 bytes ranges itself!
> 

The patch doesn't remove the support. If we are using the second 
watchpoint (PPC_DEBUG_FEATURE_DATA_BP_ARCH_31) we don't limit the 
region_size to 512 (region_size = 512) instead we use 
hwdebug_info.data_bp_alignment right? Isn't region_size that create a 
512-byte bondary?

> I think for P10 we need to continue to allow watched ranges up to
> 512 bytes in size, but they only need to be 8 byte aligned now and
> may cross a 512-byte boundary.
> 

Since the else case is region_size = hwdebug_info.data_bp_alignment;
I guess this is what it do unless I am missing something here.
> Bye,
> Ulrich
>