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From: Avi Kivity <avi@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
	Alexander Graf <agraf@suse.de>,
	Suzuki Poulose <suzuki@in.ibm.com>
Subject: Re: [PATCH 3/3] QEMU kvm/i386 : Adding KICK_VCPU capability support in i386 target.
Date: Mon, 26 Dec 2011 16:07:53 +0200	[thread overview]
Message-ID: <4EF87FB9.6060208@redhat.com> (raw)
In-Reply-To: <4EEF461E.8000107@siemens.com>

On 12/19/2011 04:11 PM, Jan Kiszka wrote:
> >>
> >> Backwards compatibility
> > 
> > If we want backwards compatibility, we need more than just a simple feature check, no? Oh, you feed that into CPUID? That's nifty. Ok, so you behave like VMX/SVM do on real hardware - you always expose the functionality but don't list it in CPUID for older user space.
>
> Do we want this to be on when providing a compat machine type ("pc-0.12"
> etc.) to the guest? Then it does need more work (see the dance around
> kvmclock).

We do.  I have a feeling the whole cpuid stuff, paravirt and
non-paravirt, needs some fixing in this area.  It's different than the
normal compat code since not only qemu, but also kvm and the host cpu
have a say in what's supported and what's not.

-- 
error compiling committee.c: too many arguments to function

WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
	Alexander Graf <agraf@suse.de>,
	Suzuki Poulose <suzuki@in.ibm.com>
Subject: Re: [Qemu-devel] [PATCH 3/3] QEMU kvm/i386 : Adding KICK_VCPU capability support in i386 target.
Date: Mon, 26 Dec 2011 16:07:53 +0200	[thread overview]
Message-ID: <4EF87FB9.6060208@redhat.com> (raw)
In-Reply-To: <4EEF461E.8000107@siemens.com>

On 12/19/2011 04:11 PM, Jan Kiszka wrote:
> >>
> >> Backwards compatibility
> > 
> > If we want backwards compatibility, we need more than just a simple feature check, no? Oh, you feed that into CPUID? That's nifty. Ok, so you behave like VMX/SVM do on real hardware - you always expose the functionality but don't list it in CPUID for older user space.
>
> Do we want this to be on when providing a compat machine type ("pc-0.12"
> etc.) to the guest? Then it does need more work (see the dance around
> kvmclock).

We do.  I have a feeling the whole cpuid stuff, paravirt and
non-paravirt, needs some fixing in this area.  It's different than the
normal compat code since not only qemu, but also kvm and the host cpu
have a say in what's supported and what's not.

-- 
error compiling committee.c: too many arguments to function

  reply	other threads:[~2011-12-26 14:07 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-04 18:25 [PATCH 0/3] QEMU kvm: Adding KICK_VCPU capability to i386 kvm Raghavendra K T
2011-12-04 18:25 ` [Qemu-devel] " Raghavendra K T
2011-12-04 18:25 ` [PATCH 1/3] QEMU kvm: Syncing linux headers to 3.2.0-rc1 Raghavendra K T
2011-12-04 18:25   ` [Qemu-devel] " Raghavendra K T
2011-12-19 13:51   ` Alexander Graf
2011-12-19 13:51     ` [Qemu-devel] " Alexander Graf
2011-12-04 18:26 ` [PATCH 2/3] QEMU kvm: Syncing linux headers to support KICK_VCPU capability Raghavendra K T
2011-12-04 18:26   ` [Qemu-devel] " Raghavendra K T
2011-12-19 13:52   ` Alexander Graf
2011-12-19 13:52     ` [Qemu-devel] " Alexander Graf
2011-12-04 18:26 ` [PATCH 3/3] QEMU kvm/i386 : Adding KICK_VCPU capability support in i386 target Raghavendra K T
2011-12-04 18:26   ` [Qemu-devel] " Raghavendra K T
2011-12-19 13:54   ` Alexander Graf
2011-12-19 13:54     ` [Qemu-devel] " Alexander Graf
2011-12-19 13:59     ` Avi Kivity
2011-12-19 13:59       ` [Qemu-devel] " Avi Kivity
2011-12-19 14:03       ` Alexander Graf
2011-12-19 14:03         ` [Qemu-devel] " Alexander Graf
2011-12-19 14:11         ` Jan Kiszka
2011-12-19 14:11           ` [Qemu-devel] " Jan Kiszka
2011-12-26 14:07           ` Avi Kivity [this message]
2011-12-26 14:07             ` Avi Kivity
2011-12-26 17:13             ` Raghavendra K T
2011-12-26 17:13               ` Raghavendra K T

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