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To: "Brian J. Johnson" <bjohnson@sgi.com>, edk2-devel@lists.01.org
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 <cd215b9c-912a-78dd-8c4c-0d52e1e4686c@sgi.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>,
 Liming Gao <liming.gao@intel.com>
From: "Zeng, Star" <star.zeng@intel.com>
Message-ID: <661df3d9-bb67-0022-3a84-c663a969d53a@intel.com>
Date: Fri, 12 Aug 2016 09:07:36 +0800
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Subject: Re: [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency
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On 2016/8/11 21:41, Brian J. Johnson wrote:
> On 08/10/2016 09:37 PM, Star Zeng wrote:
>> Minimize the code overhead between the two TSC reads by adding
>> new internal API to calculate TSC Frequency instead of reusing
>> MicroSecondDelay ().
>
> Why not just use the MSR_PLATFORM_INFO (0xce) register bits 15..8, on
> CPUs where it's available, to read the TSC frequency directly?

Per my understanding, not every generation CPU has this 
MSR_PLATFORM_INFO (0xce) register defined, and also MSR_PLATFORM_INFO 
(0xce) register bits 15..8 is just the ratio, then the radio needs to 
multiply external clock frequency which may be different for various 
generation CPU.
I believe the library's position stands as a generic library and not for 
specific CPU.


Thanks,
Star