[PATCH v2] gdb/csky support .reg2 for kernel 4.x and later

[Kevin Buettner]

On Wed, 27 Jul 2022 15:29:17 +0800
"jiangshuai_li" <jiangshuai_li@linux.alibaba.com> wrote:

> >> +      /* Supply vr0~vr15.  */
> >> +      for (i = 0; i < 16; i ++)
> >> +        {
> >> +          if (gdbarch_register_name (gdbarch, (CSKY_VR0_REGNUM + i)))
> >> +            {
> >> +              offset = 16 * i;
> >> +              regcache->raw_supply (CSKY_VR0_REGNUM + i,
> >> +                                    fregs + offset);
> >> +            }
> >> +        }
> >> +      /* Supply fr0~fr15.  */
> >> +      for (i = 0; i < 16; i ++)
> >> +        {
> >> +          if (gdbarch_register_name (gdbarch, (CSKY_FR0_REGNUM + i)))
> >> +            {
> >> +              offset = 16 * i;  
> >
> >Are these offsets correct?  I.e. do the fr0~fr15 registers use
> >the same offsets as vr0~vr15?  
> 
> Yes. The bit width of floating-point register is 64bits, and the bit width of vector
> register is 128bit. In fr0~fr15 and vr0~vr15, each FRx is the lower 64 bits of
> the corresponding VRx.

Thanks for the explanation.  You might consider adding a comment
about this if one doesn't already exist.

> >Also, not related to this patch, but while trying to figure this out,
> >I found this line in csky-tdep.h - it looks fishy to me since it's
> >way bigger than CSKY_MAX_REGS:
> >
> >  CSKY_FR16_REGNUM = 1172,  
> 
> Actually, the max regs number should be 1187, but if the gdb stub does not send a
> tdesc-xml file to gdb, 253 works.

Again, a comment regarding this fact would be nice...

Kevin