From: "Zeng, Star" <star.zeng@intel.com>
To: "Brian J. Johnson" <bjohnson@sgi.com>, edk2-devel@lists.01.org
Cc: Michael D Kinney <michael.d.kinney@intel.com>,
Liming Gao <liming.gao@intel.com>
Subject: Re: [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency
Date: Fri, 12 Aug 2016 09:07:36 +0800 [thread overview]
Message-ID: <661df3d9-bb67-0022-3a84-c663a969d53a@intel.com> (raw)
In-Reply-To: <cd215b9c-912a-78dd-8c4c-0d52e1e4686c@sgi.com>
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
next prev parent reply other threads:[~2016-08-12 1:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-11 2:37 [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency Star Zeng
2016-08-11 2:42 ` Gao, Liming
2016-08-11 5:01 ` Kinney, Michael D
2016-08-11 13:41 ` Brian J. Johnson
2016-08-12 1:07 ` Zeng, Star [this message]
2016-08-12 8:31 ` Paolo Bonzini
2016-08-12 8:43 ` Zeng, Star
2016-08-12 18:27 ` Kinney, Michael D
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