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    SubjectRE: [PATCH V2 1/1] X86: Hyper-V: Get the local APIC timer frequency from the hypervisor
    Date


    > -----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
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