Re: [kvm-unit-tests PATCH v3 1/1] s390x: verify EQBS/SQBS is unavailable

[Nico Boehr <nrb@linux.ibm.com>]

Quoting Thomas Huth (2022-08-04 00:17:38)
> On 03/08/2022 15.58, Nico Boehr wrote:
> > QEMU doesn't provide EQBS/SQBS instructions, so we should check they
> > result in an exception.
> 
> I somewhat fail to see the exact purpose of this patch... QEMU still doesn't 
> emulate a lot of other instructions, too, so why are we checking now these 
> QBS instructions? 

I agree with you, it certainly doesn't make sense to test all kinds of random instructions that aren't implemented in QEMU.

But, for the QBS instructions, there is a special case in handle_b9 and handle_eb in QEMU. I would argue since there is code for it, there can be (or even should be) tests for it.

But if you guys say it is not worth having this test, this is fine for me as well.

[...]
> > diff --git a/s390x/intercept.c b/s390x/intercept.c
> > index 9e826b6c79ad..48eb2d22a2cc 100644
> > --- a/s390x/intercept.c
> > +++ b/s390x/intercept.c
> > @@ -197,6 +197,34 @@ static void test_diag318(void)
> >   
> >   }
> >   
> > +static void test_qbs(void)
> > +{
> > +     report_prefix_push("qbs");
> 
> You should definitely add a comment here, explaining why this is only a test 
> for QEMU and saying that this could be removed as soon as QEMU implements 
> these instructions later - otherwise this would be very confusing to the 
> readers later (if they forget or cannot check the commit message).

OK, I can add this once we have an answer to your first question.