[Qemu-devel] Re: [PATCH 1/2] hw/arm_sysctl.c: Add the Versatile Express system registers

[Juan Quintela <quintela@redhat.com>]

Peter Maydell <peter.maydell@linaro.org> wrote:

Hi

> @@ -41,6 +44,9 @@ static const VMStateDescription vmstate_arm_sysctl = {
>          VMSTATE_UINT32(flags, arm_sysctl_state),
>          VMSTATE_UINT32(nvflags, arm_sysctl_state),
>          VMSTATE_UINT32(resetlevel, arm_sysctl_state),
> +        VMSTATE_UINT32(sys_cfgdata, arm_sysctl_state),
> +        VMSTATE_UINT32(sys_cfgctrl, arm_sysctl_state),
> +        VMSTATE_UINT32(sys_cfgstat, arm_sysctl_state),
>          VMSTATE_END_OF_LIST()
>      }
>  };

Three options (about migration):
- left things as they are and become incompatible without changing versions
- if you don't care about backward compatibility, just add +1 to all the
  version fields and you are done.
- add this fields only for the new version.

IMHO 1st one is the worse option.  I will go with the middle one (as far
as I know, nobody on arm uses interversion migration (as far as I know,
nobody uses migration at all).

If you (or anybody else does), a pointer to one setup that is known to
work is welcome.

Later, Juan.