From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2 4/4] RTC:Add UIP(update in progress) check logic Date: Mon, 20 Feb 2012 08:40:04 +0100 Message-ID: <4F41F8D4.9080500@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "qemu-devel@nongnu.org" , Jan Kiszka , "kvm@vger.kernel.org" , "aliguori@us.ibm.com" , Marcelo Tosatti To: "Zhang, Yang Z" Return-path: Received: from mail-ee0-f46.google.com ([74.125.83.46]:53483 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750905Ab2BTHkH (ORCPT ); Mon, 20 Feb 2012 02:40:07 -0500 Received: by eekc14 with SMTP id c14so2129174eek.19 for ; Sun, 19 Feb 2012 23:40:06 -0800 (PST) In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 02/20/2012 01:25 AM, Zhang, Yang Z wrote: > When time base is 32kHz, the update cycle takes 1984us at the end > of every second. And the update cycle begins 244us later after UIP > is set. So the UIP is set in 2228us at end of every second. I think we can keep UIP set only for 244us, since our update cycle is instantaneous. Otherwise looks good, thanks! Paolo > Signed-off-by: Yang Zhang > > --- > hw/mc146818rtc.c | 26 ++++++++++++++++++++++++++ > 1 files changed, 26 insertions(+), 0 deletions(-) > > diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c > index 2445c6b..d4be8e9 100644 > --- a/hw/mc146818rtc.c > +++ b/hw/mc146818rtc.c > @@ -601,6 +601,29 @@ static void rtc_calibrate_time(RTCState *s) > s->current_tm = *ret; > } > > +static int update_in_progress(RTCState *s) > +{ > + struct timeval tv_now; > + int64_t host_usec, offset_usec, guest_usec; > + > + if (s->cmos_data[RTC_REG_B] & REG_B_SET) { > + return 0; > + } > + > + gettimeofday(&tv_now, NULL); > + host_usec = tv_now.tv_sec * USEC_PER_SEC + tv_now.tv_usec; > + offset_usec = s->offset_sec * USEC_PER_SEC + s->offset_usec; > + guest_usec = host_usec + offset_usec; > + > + /* UIP bit will be set at last 2228us of every second. > + * Only consider oscillator in 32.768kHz*/ > + if ((guest_usec % USEC_PER_SEC) >= (USEC_PER_SEC - 2228)) { > + return 1; > + }