Re: [Qemu-devel] [RFC PATCH 3/3] s390x/css: add hint for devno missmatch

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Halil Pasic (pasic@linux.vnet.ibm.com) wrote:
> 
> 
> On 06/07/2017 01:22 PM, Dr. David Alan Gilbert wrote:
> > * Halil Pasic (pasic@linux.vnet.ibm.com) wrote:
> >> This one has to be fixed up to 's390x: vmstatify config migration for
> >> virtio-ccw' provided we want to achieve the same as 's390x/css: catch
> >> section mismatch on load' does.
> >>
> >> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> >> ---
> >>
> >> This is on tom of 's390x: vmstatify config migration for virtio-ccw'
> >                p
> >> which ain't on top of 's390x/css: catch section mismatch on load' but on
> >> top of master.  I kind of have a circular dependency here. This is why
> >> the series is RFC. 
> >>
> >> Wanted to provide an usage example. Faked 'Re: ' so patchew does not
> >> try to apply this on top of current master.
> >> ---
> >>  hw/s390x/css.c | 6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> >> index 348129e1b2..de277d6a3d 100644
> >> --- a/hw/s390x/css.c
> >> +++ b/hw/s390x/css.c
> >> @@ -134,6 +134,10 @@ static const VMStateDescription vmstate_sense_id = {
> >>  static int subch_dev_post_load(void *opaque, int version_id);
> >>  static void subch_dev_pre_save(void *opaque);
> >>  
> >> +const char err_hint_devno[] = "Devno mismatch, tried to load wrong section!"
> >> +    " Likely reason: some sequences of plug and unplug  can break"
> >> +    " migration for machine versions prior to  2.7 (known design flaw).";
> >> +
> > 
> > That's ok, but I suggest:
> >    * 'bug' rather than 'design flaw' - it sounds a bit less scary to
> >      endusers.
> > 
> 
> I do not think it can be changed now. Christian as already sent out a pull
> request for the patch this series is re-doing with vmstate.  That patch has the
> same error message. I have considered bug but decided against because
> the 'bug' can't be fixed. I think it's pretty hard to hit this with normal
> usage (and that's probably the reason why it went undetected until recently),
> so hope not too may endusers are going to get scared by developer honesty :).

No problem; it's your device anyway :-)

> > Other than that,
> > 
> > 
> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> Great thanks for the review!

Dave

> Halil
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK