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From: Paolo Bonzini <pbonzini@redhat.com>
To: "Zhang, Yang Z" <yang.z.zhang@intel.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Jan Kiszka <jan.kiszka@web.de>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"aliguori@us.ibm.com" <aliguori@us.ibm.com>,
	Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH v2 2/4] RTC:Add RTC update-ended interrupt logic
Date: Mon, 20 Feb 2012 08:38:20 +0100	[thread overview]
Message-ID: <4F41F86C.8010801@redhat.com> (raw)
In-Reply-To: <A9667DDFB95DB7438FA9D7D576C3D87E071FF3@SHSMSX101.ccr.corp.intel.com>

On 02/20/2012 01:25 AM, Zhang, Yang Z wrote:
> Use timer to emulate RTC update-ended interrupt. The timer is enabled
> only when UIE is setting.

The timer needs to be enabled when UF is clear, not when UIE is set.  If
UIE is set but the update interrupt is masked you do not need to do
anything; on the other hand you need to update UF in case the guest is
observing interrupts with polling.

Paolo

WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: "Zhang, Yang Z" <yang.z.zhang@intel.com>
Cc: "aliguori@us.ibm.com" <aliguori@us.ibm.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Jan Kiszka <jan.kiszka@web.de>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [Qemu-devel] [PATCH v2 2/4] RTC:Add RTC update-ended interrupt logic
Date: Mon, 20 Feb 2012 08:38:20 +0100	[thread overview]
Message-ID: <4F41F86C.8010801@redhat.com> (raw)
In-Reply-To: <A9667DDFB95DB7438FA9D7D576C3D87E071FF3@SHSMSX101.ccr.corp.intel.com>

On 02/20/2012 01:25 AM, Zhang, Yang Z wrote:
> Use timer to emulate RTC update-ended interrupt. The timer is enabled
> only when UIE is setting.

The timer needs to be enabled when UF is clear, not when UIE is set.  If
UIE is set but the update interrupt is masked you do not need to do
anything; on the other hand you need to update UF in case the guest is
observing interrupts with polling.

Paolo

  reply	other threads:[~2012-02-20  7:38 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-20  0:25 [PATCH v2 2/4] RTC:Add RTC update-ended interrupt logic Zhang, Yang Z
2012-02-20  0:25 ` [Qemu-devel] " Zhang, Yang Z
2012-02-20  7:38 ` Paolo Bonzini [this message]
2012-02-20  7:38   ` Paolo Bonzini
2012-02-20 23:55   ` Zhang, Yang Z
2012-02-20 23:55     ` [Qemu-devel] " Zhang, Yang Z

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