Re: [ping 2] [RFA][PATCH v4 0/5] Add TDB regset support

[Andreas Arnez <arnez@linux.vnet.ibm.com>]

"Ulrich Weigand" <uweigand@de.ibm.com> writes:

> Your patch below doesn't show the common code changes, so I'm not
> sure how you planned to handle legacy platforms.  I guess it might
> be possible to detect them using zero markers in those fields ...

Right, before coming up with a complete patch I wanted to get some
feedback on this general idea.  So I guess it's worth giving it a try?

> As an aside, I'm wondering:
>
>> +  res = cb (tdep->wordsize == 4 ?
>> +	    &ppc32_linux_gregset : &ppc64_linux_gregset,
>> +	    cb_data);
>> +  if (!res)
>> +    res = cb (&ppc32_linux_fpregset, cb_data);
>> +  if (!res && have_altivec)
>> +    res = cb (&ppc32_linux_vrregset, cb_data);
>> +  if (!res && have_vsx)
>> +    cb (&ppc32_linux_vsxregset, cb_data);
>
> Why does the callback need to return a flag that has to be handled
> by the caller?   If there is indeed a requirement for treating
> error conditions specially, couldn't the callback store error data
> in the cb_data and handle it on subsequent calls?

This is a good point.  Yes, this is for error handling, and yes, the
error indication could be moved to cb_data.

> This would make the gdbarch implementations in the targets yet
> easier and simpler to write, something along the lines of:
>
>   if (tdep->wordsize == 4)
>     cb (&ppc32_linux_gregset, cb_data);
>   else
>     cb (&ppc64_linux_gregset, cb_data);
>   cb (&ppc32_linux_fpregset, cb_data);
>   if (have_altivec)
>     cb (&ppc32_linux_vrregset, cb_data);
>   if (have_vsx)
>     cb (&ppc32_linux_vsxregset, cb_data);

Yup.