Re: [Qemu-devel] [PATCH v3 2/6] suspend: switch acpi s3 to new infrastructure.

From: Gleb Natapov <gleb@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: xen-devel@lists.xensource.com, Gerd Hoffmann <kraxel@redhat.com>,
	qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v3 2/6] suspend: switch acpi s3 to new infrastructure.
Date: Thu, 9 Feb 2012 14:31:57 +0200	[thread overview]
Message-ID: <20120209123157.GJ18866@redhat.com> (raw)
In-Reply-To: <4F33AB4D.9070904@redhat.com>

On Thu, Feb 09, 2012 at 12:17:33PM +0100, Paolo Bonzini wrote:
> On 02/08/2012 12:00 PM, Gerd Hoffmann wrote:
> >+/* set CMOS shutdown status register (index 0xF) as S3_resume(0xFE)
> >+   BIOS will read it and start S3 resume at POST Entry */
> >+static void rtc_notify_suspend(Notifier *notifier, void *data)
> >+{
> >+    RTCState *s = container_of(notifier, RTCState, suspend_notifier);
> >+    rtc_set_memory(&s->dev, 0xF, 0xFE);
> >+}
> >+
> 
> Out of curiosity, who would set this on real hardware?  And since
Real HW may have other ways to notify BIOS that system was S3 suspended
(special chipset register for instance). I think we can write DSDT magic
to write RTC for us, but I prefer to do it from inside QEMU.

> RTC memory is nvram, what happens if I remove the mains plug while
> the system is in S3?
> 
RTC is battery backed, but what do you expect will happen to main memory
where all your data resides during S3 in this case anyway?

--
			Gleb.