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From: Thomas Huth <thuth@redhat.com>
To: Greg Kurz <groug@kaod.org>, David Gibson <david@gibson.dropbear.id.au>
Cc: qemu-devel@nongnu.org, "Cédric Le Goater" <clg@kaod.org>
Subject: Re: [Qemu-devel] [PATCH for-3.1] tests/cpu-plug-test: check CPU hotplug on ppc64 with KVM
Date: Fri, 27 Jul 2018 10:18:14 +0200	[thread overview]
Message-ID: <f43c94da-43d1-7621-1997-00407708d496@redhat.com> (raw)
In-Reply-To: <20180727095452.45edee8b@bahia>

On 07/27/2018 09:54 AM, Greg Kurz wrote:
> On Fri, 27 Jul 2018 15:27:24 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
>> On Wed, Jul 25, 2018 at 04:45:26PM +0200, Greg Kurz wrote:
>>> Commit b585395b655 fixed a regression introduced by some recent changes
>>> in the XICS code, that was causing QEMU to crash instantly during CPU
>>> hotplug with KVM. This is typically the kind of bug we'd like our
>>> test suite to detect before it gets merged. Unfortunately, the current
>>> tests run with '-machine accel=qtest' and don't exercise KVM specific
>>> paths in QEMU.
>>>
>>> This patch hence changes add_pseries_test_case() to launch QEMU with
>>> '-machine accel=kvm' if KVM is available.
>>>
>>> A notable consequence is that the guest will execute SLOF, but for some
>>> reasons SLOF sometimes hits a program exception. This causes the guest
>>> to loop forever and the test to be stuck.  Since we don't need the guest
>>> to be truely running, let's pass -S to QEMU to avoid that.
>>>
>>> Also disable machine capabilities that could be unavailable in KVM, eg,
>>> when using PR KVM.
>>>
>>> Signed-off-by: Greg Kurz <groug@kaod.org>  
>>
>> I'm pretty sure trying to change the accelerator on a qtest test just
>> doesn't make sense.  We'd need a different approach for testing cpu
>> hotplug against kvm & tcg backends.
>>
> 
> The test starts QEMU, triggers the CPU hotplug code with a QMP command
> and checks the command didn't fail (or QEMU didn't crash, as it would
> have before commit b585395b655a)... I really don't understand what
> is wrong with that... Please elaborate.

For a "real" test, I think you'd need a guest OS that is reacting to the
hot plug events. So maybe this should rather be done in the avocado
framework instead?

 Thomas

  reply	other threads:[~2018-07-27  8:18 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-25 14:45 [Qemu-devel] [PATCH for-3.1] tests/cpu-plug-test: check CPU hotplug on ppc64 with KVM Greg Kurz
2018-07-27  5:27 ` David Gibson
2018-07-27  7:54   ` Greg Kurz
2018-07-27  8:18     ` Thomas Huth [this message]
2018-07-27  9:00       ` Greg Kurz
2018-07-27 11:25         ` Thomas Huth
2018-07-27 12:03           ` Greg Kurz
2018-07-30  5:57     ` David Gibson
2018-07-30  8:41       ` Greg Kurz
2018-07-30  9:59         ` Greg Kurz
2018-07-31  3:27           ` David Gibson
2018-08-01 13:35             ` Greg Kurz
2018-07-31  3:25         ` David Gibson
2018-08-01 13:24           ` Greg Kurz
2018-08-02  4:08             ` David Gibson
2018-08-02  9:36             ` Igor Mammedov
2018-08-02 10:52               ` Greg Kurz

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