Re: [Qemu-devel] [PULL 42/43] piix4: add acpi pci hotplug support

[Paolo Bonzini <pbonzini@redhat.com>]

Il 16/10/2013 20:37, Michael S. Tsirkin ha scritto:
> Gleb, Paolo, what do you think? OK to merge kvm unit test
> into qemu? It depends on qemu anyway, in-tree will make it easier.
> Maybe someone's looking at this already?

I think merging KVM unit tests doesn't make much sense because, with
some small exceptions, it is mostly a test or a benchmark for KVM.  What
may make sense is to have a quick way to run autotest on a QEMU tree,
with a subset of testcases that doesn't take too much time (let's say <4
hours) and is more or less guaranteed to pass.  KVM unit tests are run
by autotest, that should be enough.

I agree with Anthony that device model code should be tested by qtest.
I'm not sure this extends to firmware interfaces, though, for two reasons:

(1) any testcase you could have written would have likely not shown the
kind of problem that Igor and Gerd found in your previous versions.
Black box unit testing can only do so much for something as complex as a
DSDT, while black box integration testing works well.

(2) IMO qtest's main advantage is that, at least in principle, the same
testcases could run on all the rarely-used almost-unmaintained targets
(the endianness-test already does that for example).  This does not
apply to most firmware interfaces, though.


By the way, this advantage of qtest is also being mostly negated by the
immaturity (or sheer absence) of infrastructure.

Looking at bugs that were reported, at least these two from Igor are
probably best handled with integration tests (like autotest or Anthony's
qemu-test):

* WS2008R2x64 BSODs with ACPI error on boot when 64bit PCI hole is
present, but it boots fine with upstream QEMU

* hotadd CPU to guest, reboot guest, only initial CPUs are visible to guest


qtest could at best host some sanity checks on the ACPI tables, which
would catch the MCFG problems that Gerd reported on v5.

Gerd also reported some segfaults, not sure how they escaped mst's
testing so I cannot judge what kind of testing could have exposed them
preemptively.

Paolo