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From: Marc Zyngier <marc.zyngier@arm.com>
To: Andre Przywara <andre.przywara@arm.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: Alexander Graf <graf@amazon.com>,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: Re: [PATCH kvm-unit-tests] arm: Add PL031 test
Date: Thu, 11 Jul 2019 10:52:26 +0100	[thread overview]
Message-ID: <75578652-0396-d349-3d81-da7190e2d714@arm.com> (raw)
In-Reply-To: <20190711104200.254073fb@donnerap.cambridge.arm.com>

On 11/07/2019 10:42, Andre Przywara wrote:
> On Thu, 11 Jul 2019 09:52:42 +0200
> Paolo Bonzini <pbonzini@redhat.com> wrote:
> 
> Hi,
> 
>> On 11/07/19 07:49, Alexander Graf wrote:
>>>> I agree that it would belong more in qtest, but tests in not exactly the
>>>> right place is better than no tests.  
>>>
>>> The problem with qtest is that it tests QEMU device models from a QEMU
>>> internal view.  
>>
>> Not really: fundamentally it tests QEMU device models with stimuli that
>> come from another process in the host, rather than code that runs in a
>> guest.  It does have hooks into QEMU's internal view (mostly to
>> intercept interrupts and advance the clocks), but the main feature of
>> the protocol is the ability to do memory reads and writes.
>>
>>> I am much more interested in the guest visible side of things. If
>>> kvmtool wanted to implement a PL031, it should be able to execute the
>>> same test that we run against QEMU, no?  
> 
> One of the design goals of kvmtool is to get away with as little emulation
> as possible, in favour of paravirtualisation (so it's just virtio and not
> IDE/flash). So a hardware RTC emulation sounds dispensable in this context.

Funnily enough, kvmtool does have a RTC emulation (MC146818). The
support code in Linux is so braindead that I gave up on it about 5 years
ago.

	M.
-- 
Jazz is not dead. It just smells funny...
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  reply	other threads:[~2019-07-11  9:52 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-10 13:27 [PATCH kvm-unit-tests] arm: Add PL031 test Alexander Graf
2019-07-10 14:25 ` Marc Zyngier
2019-07-12  8:29   ` Alexander Graf
2019-07-12  8:51     ` Marc Zyngier
2019-07-10 14:37 ` Alexandru Elisei
2019-07-10 17:02 ` Andre Przywara
2019-07-10 17:06   ` Paolo Bonzini
2019-07-11  5:49     ` Alexander Graf
2019-07-11  7:52       ` Paolo Bonzini
2019-07-11  9:42         ` Andre Przywara
2019-07-11  9:52           ` Marc Zyngier [this message]
2019-07-11  9:59           ` Alexander Graf
2019-07-11  8:51 ` Peter Maydell
2019-07-11  9:11   ` Alexander Graf
2019-07-11  9:13     ` Peter Maydell

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