RE: [PATCH V2 1/1] X86: Hyper-V: Get the local APIC timer frequencyfrom the hypervisor

[KY Srinivasan]

> -----Original Message-----
> From: Olaf Hering [mailto:olaf@xxxxxxxxx]
> Sent: Friday, September 27, 2013 8:10 AM
> To: KY Srinivasan
> Cc: x86@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx;
> tglx@xxxxxxxxxxxxx; hpa@xxxxxxxxx; JBeulich@xxxxxxxx; bp@xxxxxxxxx
> 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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