Re: [Qemu-devel] [PATCH for-2.6] ppc: Fix migration of the XER register

[Thomas Huth <thuth@redhat.com>]

On 15.04.2016 12:17, Mark Cave-Ayland wrote:
> On 15/04/16 10:03, Thomas Huth wrote:
> 
>> env->xer only holds the lower bits of the XER register nowadays, the
>> SO, OV and CA bits are stored in separate variables (see the function
>> cpu_write_xer() for details). Since the migration code currently only
>> reads the "xer" variable, the upper bits are lost during migration.
>> Fix it by using cpu_read_xer() instead.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
> 
> This looks like the pre_save counterpart to the post_load patch I sent
> in January (see 6a9620e60cc1b16dba9ee9d9d8cb374e4303c072) so I'm fairly
> sure this is right.

Ah, ok, that's why the load part was already right :-)

Looks like the cpu_read/write_xer() functions have originally been
introduced in da91a00f ("Split out SO, OV, CA fields from XER"), and
this patch also used it for the load and save functions in machine.c.
However, a little bit later, the functions had been changed to use
VMState instead (see a90db158 - "Convert ppc cpu savevm to
VMStateDescription"), and the cpu_read/write_xer() calls accidentally
got dropped in this patch. So introducing them again now is really the
right thing to do.

> Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

 Thanks!
  Thomas