From: KY Srinivasan <kys@microsoft.com>
To: Olaf Hering <olaf@aepfle.de>
CC: "x86@kernel.org" <x86@kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
        "apw@canonical.com" <apw@canonical.com>,
        "jasowang@redhat.com" <jasowang@redhat.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "hpa@zytor.com" <hpa@zytor.com>,
        "JBeulich@suse.com" <JBeulich@suse.com>, "bp@alien8.de" <bp@alien8.de>
Subject: RE: [PATCH V2 1/1] X86: Hyper-V: Get the local APIC timer frequency
 from the hypervisor
Thread-Topic: [PATCH V2 1/1] X86: Hyper-V: Get the local APIC timer
 frequency from the hypervisor
Thread-Index: AQHOqM30I+mkPB2b1kKq/5YqjRysqJnZ1ccAgAADeVA=
Date: Fri, 27 Sep 2013 15:23:17 +0000
Message-ID: <418dd0e9b1054189b61770edb57c5b37@SN2PR03MB061.namprd03.prod.outlook.com>
References: <1378233023-4512-1-git-send-email-kys@microsoft.com>
 <20130927151026.GA29416@aepfle.de>
In-Reply-To: <20130927151026.GA29416@aepfle.de>
Accept-Language: en-US
Content-Language: en-US
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Sender: linux-kernel-owner@vger.kernel.org
Content-Transfer-Encoding: 8bit
Content-Length: 1475
Lines: 42


> -----Original Message-----
> From: Olaf Hering [mailto:olaf@aepfle.de]
> Sent: Friday, September 27, 2013 8:10 AM
> To: KY Srinivasan
> Cc: x86@kernel.org; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; apw@canonical.com; jasowang@redhat.com;
> tglx@linutronix.de; hpa@zytor.com; JBeulich@suse.com; bp@alien8.de
> Subject: Re: [PATCH V2 1/1] X86: Hyper-V: Get the local APIC timer frequency
> from the hypervisor
> 
> On Tue, Sep 03, K. Y. Srinivasan wrote:
> 
> > Hyper-V supports a mechanism for retrieving the local APIC frequency.Use this
> and bypass
> > the calibration code in the kernel. This would allow us to boot the Linux kernel
> as a
> > "modern VM" on Hyper-V where many of the legacy devices (such as PIT) are
> not emulated.
> 
> > +	if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
> > +		/*
> > +		 * Get the APIC frequency.
> > +		 */
> > +		rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
> > +		hv_lapic_frequency /= HZ;
> 
> This leads to build errors on 32bit:
> 
> linux-3.12-rc2/arch/x86/kernel/cpu/mshyperv.c:88: undefined reference to
> `__udivdi3'
> 
> Up to now I have only tested on 64bit, sorry for that.

Thanks Olaf. I am travelling currently; I will fix it when I get back (early next week).

K. Y
> 
> 
> Olaf
????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m????????????I?